figure:last-child { margin-bottom: 0.5rem; }
#write ol, #write ul { position: relative; }
img { max-width: 100%; vertical-align: middle; }
button, input, select, textarea { color: inherit; font: inherit; }
input[type="checkbox"], input[type="radio"] { line-height: normal; padding: 0px; }
*, ::after, ::before { box-sizing: border-box; }
#write h1, #write h2, #write h3, #write h4, #write h5, #write h6, #write p, #write pre { width: inherit; }
#write h1, #write h2, #write h3, #write h4, #write h5, #write h6, #write p { position: relative; }
p { line-height: inherit; }
h1, h2, h3, h4, h5, h6 { break-after: avoid-page; break-inside: avoid; orphans: 2; }
p { orphans: 4; }
h1 { font-size: 2rem; }
h2 { font-size: 1.8rem; }
h3 { font-size: 1.6rem; }
h4 { font-size: 1.4rem; }
h5 { font-size: 1.2rem; }
h6 { font-size: 1rem; }
.md-math-block, .md-rawblock, h1, h2, h3, h4, h5, h6, p { margin-top: 1rem; margin-bottom: 1rem; }
.hidden { display: none; }
.md-blockmeta { color: rgb(204, 204, 204); font-weight: 700; font-style: italic; }
a { cursor: pointer; }
sup.md-footnote { padding: 2px 4px; background-color: rgba(238, 238, 238, 0.7); color: rgb(85, 85, 85); border-radius: 4px; cursor: pointer; }
sup.md-footnote a, sup.md-footnote a:hover { color: inherit; text-transform: inherit; text-decoration: inherit; }
#write input[type="checkbox"] { cursor: pointer; width: inherit; height: inherit; }
figure { overflow-x: auto; margin: 1.2em 0px; max-width: calc(100% + 16px); padding: 0px; }
figure > table { margin: 0px !important; }
tr { break-inside: avoid; break-after: auto; }
thead { display: table-header-group; }
table { border-collapse: collapse; border-spacing: 0px; width: 100%; overflow: auto; break-inside: auto; text-align: left; }
table.md-table td { min-width: 32px; }
.CodeMirror-gutters { border-right: 0px; background-color: inherit; }
.CodeMirror-linenumber { user-select: none; }
.CodeMirror { text-align: left; }
.CodeMirror-placeholder { opacity: 0.3; }
.CodeMirror pre { padding: 0px 4px; }
.CodeMirror-lines { padding: 0px; }
div.hr:focus { cursor: none; }
#write pre { white-space: pre-wrap; }
#write.fences-no-line-wrapping pre { white-space: pre; }
#write pre.ty-contain-cm { white-space: normal; }
.CodeMirror-gutters { margin-right: 4px; }
.md-fences { font-size: 0.9rem; display: block; break-inside: avoid; text-align: left; overflow: visible; white-space: pre; background: inherit; position: relative !important; }
.md-diagram-panel { width: 100%; margin-top: 10px; text-align: center; padding-top: 0px; padding-bottom: 8px; overflow-x: auto; }
#write .md-fences.mock-cm { white-space: pre-wrap; }
.md-fences.md-fences-with-lineno { padding-left: 0px; }
#write.fences-no-line-wrapping .md-fences.mock-cm { white-space: pre; overflow-x: auto; }
.md-fences.mock-cm.md-fences-with-lineno { padding-left: 8px; }
.CodeMirror-line, twitterwidget { break-inside: avoid; }
.footnotes { opacity: 0.8; font-size: 0.9rem; margin-top: 1em; margin-bottom: 1em; }
.footnotes + .footnotes { margin-top: 0px; }
.md-reset { margin: 0px; padding: 0px; border: 0px; outline: 0px; vertical-align: top; background: 0px 0px; text-decoration: none; text-shadow: none; float: none; position: static; width: auto; height: auto; white-space: nowrap; cursor: inherit; -webkit-tap-highlight-color: transparent; line-height: normal; font-weight: 400; text-align: left; box-sizing: content-box; direction: ltr; }
li div { padding-top: 0px; }
blockquote { margin: 1rem 0px; }
li .mathjax-block, li p { margin: 0.5rem 0px; }
li { margin: 0px; position: relative; }
blockquote > :last-child { margin-bottom: 0px; }
blockquote > :first-child, li > :first-child { margin-top: 0px; }
.footnotes-area { color: rgb(136, 136, 136); margin-top: 0.714rem; padding-bottom: 0.143rem; white-space: normal; }
#write .footnote-line { white-space: pre-wrap; }
@media print {
body, html { border: 1px solid transparent; height: 99%; break-after: avoid; break-before: avoid; }
#write { margin-top: 0px; padding-top: 0px; border-color: transparent !important; }
.typora-export * { -webkit-print-color-adjust: exact; }
html.blink-to-pdf { font-size: 13px; }
.typora-export #write { padding-left: 32px; padding-right: 32px; padding-bottom: 0px; break-after: avoid; }
.typora-export #write::after { height: 0px; }
}
.footnote-line { margin-top: 0.714em; font-size: 0.7em; }
a img, img a { cursor: pointer; }
pre.md-meta-block { font-size: 0.8rem; min-height: 0.8rem; white-space: pre-wrap; background: rgb(204, 204, 204); display: block; overflow-x: hidden; }
p > .md-image:only-child:not(.md-img-error) img, p > img:only-child { display: block; margin: auto; }
p > .md-image:only-child { display: inline-block; width: 100%; }
#write .MathJax_Display { margin: 0.8em 0px 0px; }
.md-math-block { width: 100%; }
.md-math-block:not(:empty)::after { display: none; }
[contenteditable="true"]:active, [contenteditable="true"]:focus { outline: 0px; box-shadow: none; }
.md-task-list-item { position: relative; list-style-type: none; }
.task-list-item.md-task-list-item { padding-left: 0px; }
.md-task-list-item > input { position: absolute; top: 0px; left: 0px; margin-left: -1.2em; margin-top: calc(1em - 10px); border: none; }
.math { font-size: 1rem; }
.md-toc { min-height: 3.58rem; position: relative; font-size: 0.9rem; border-radius: 10px; }
.md-toc-content { position: relative; margin-left: 0px; }
.md-toc-content::after, .md-toc::after { display: none; }
.md-toc-item { display: block; color: rgb(65, 131, 196); }
.md-toc-item a { text-decoration: none; }
.md-toc-inner:hover { text-decoration: underline; }
.md-toc-inner { display: inline-block; cursor: pointer; }
.md-toc-h1 .md-toc-inner { margin-left: 0px; font-weight: 700; }
.md-toc-h2 .md-toc-inner { margin-left: 2em; }
.md-toc-h3 .md-toc-inner { margin-left: 4em; }
.md-toc-h4 .md-toc-inner { margin-left: 6em; }
.md-toc-h5 .md-toc-inner { margin-left: 8em; }
.md-toc-h6 .md-toc-inner { margin-left: 10em; }
@media screen and (max-width: 48em) {
.md-toc-h3 .md-toc-inner { margin-left: 3.5em; }
.md-toc-h4 .md-toc-inner { margin-left: 5em; }
.md-toc-h5 .md-toc-inner { margin-left: 6.5em; }
.md-toc-h6 .md-toc-inner { margin-left: 8em; }
}
a.md-toc-inner { font-size: inherit; font-style: inherit; font-weight: inherit; line-height: inherit; }
.footnote-line a:not(.reversefootnote) { color: inherit; }
.md-attr { display: none; }
.md-fn-count::after { content: "."; }
code, pre, samp, tt { font-family: var(--monospace); }
kbd { margin: 0px 0.1em; padding: 0.1em 0.6em; font-size: 0.8em; color: rgb(36, 39, 41); background: rgb(255, 255, 255); border: 1px solid rgb(173, 179, 185); border-radius: 3px; box-shadow: rgba(12, 13, 14, 0.2) 0px 1px 0px, rgb(255, 255, 255) 0px 0px 0px 2px inset; white-space: nowrap; vertical-align: middle; }
.md-comment { color: rgb(162, 127, 3); opacity: 0.8; font-family: var(--monospace); }
code { text-align: left; vertical-align: initial; }
a.md-print-anchor { white-space: pre !important; border-width: initial !important; border-style: none !important; border-color: initial !important; display: inline-block !important; position: absolute !important; width: 1px !important; right: 0px !important; outline: 0px !important; background: 0px 0px !important; text-decoration: initial !important; text-shadow: initial !important; }
.md-inline-math .MathJax_SVG .noError { display: none !important; }
.html-for-mac .inline-math-svg .MathJax_SVG { vertical-align: 0.2px; }
.md-math-block .MathJax_SVG_Display { text-align: center; margin: 0px; position: relative; text-indent: 0px; max-width: none; max-height: none; min-height: 0px; min-width: 100%; width: auto; overflow-y: hidden; display: block !important; }
.MathJax_SVG_Display, .md-inline-math .MathJax_SVG_Display { width: auto; margin: inherit; display: inline-block !important; }
.MathJax_SVG .MJX-monospace { font-family: var(--monospace); }
.MathJax_SVG .MJX-sans-serif { font-family: sans-serif; }
.MathJax_SVG { display: inline; font-style: normal; font-weight: 400; line-height: normal; zoom: 90%; text-indent: 0px; text-align: left; text-transform: none; letter-spacing: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; }
.MathJax_SVG * { transition: none 0s ease 0s; }
.MathJax_SVG_Display svg { vertical-align: middle !important; margin-bottom: 0px !important; margin-top: 0px !important; }
.os-windows.monocolor-emoji .md-emoji { font-family: "Segoe UI Symbol", sans-serif; }
.md-diagram-panel > svg { max-width: 100%; }
[lang="mermaid"] svg, [lang="flow"] svg { max-width: 100%; height: auto; }
[lang="mermaid"] .node text { font-size: 1rem; }
table tr th { border-bottom: 0px; }
video { max-width: 100%; display: block; margin: 0px auto; }
iframe { max-width: 100%; width: 100%; border: none; }
.highlight td, .highlight tr { border: 0px; }
.CodeMirror { height: auto; }
.CodeMirror.cm-s-inner { background: inherit; }
.CodeMirror-scroll { overflow: auto hidden; z-index: 3; }
.CodeMirror-gutter-filler, .CodeMirror-scrollbar-filler { background-color: rgb(255, 255, 255); }
.CodeMirror-gutters { border-right: 1px solid rgb(221, 221, 221); background: inherit; white-space: nowrap; }
.CodeMirror-linenumber { padding: 0px 3px 0px 5px; text-align: right; color: rgb(153, 153, 153); }
.cm-s-inner .cm-keyword { color: rgb(119, 0, 136); }
.cm-s-inner .cm-atom, .cm-s-inner.cm-atom { color: rgb(34, 17, 153); }
.cm-s-inner .cm-number { color: rgb(17, 102, 68); }
.cm-s-inner .cm-def { color: rgb(0, 0, 255); }
.cm-s-inner .cm-variable { color: rgb(0, 0, 0); }
.cm-s-inner .cm-variable-2 { color: rgb(0, 85, 170); }
.cm-s-inner .cm-variable-3 { color: rgb(0, 136, 85); }
.cm-s-inner .cm-string { color: rgb(170, 17, 17); }
.cm-s-inner .cm-property { color: rgb(0, 0, 0); }
.cm-s-inner .cm-operator { color: rgb(152, 26, 26); }
.cm-s-inner .cm-comment, .cm-s-inner.cm-comment { color: rgb(170, 85, 0); }
.cm-s-inner .cm-string-2 { color: rgb(255, 85, 0); }
.cm-s-inner .cm-meta { color: rgb(85, 85, 85); }
.cm-s-inner .cm-qualifier { color: rgb(85, 85, 85); }
.cm-s-inner .cm-builtin { color: rgb(51, 0, 170); }
.cm-s-inner .cm-bracket { color: rgb(153, 153, 119); }
.cm-s-inner .cm-tag { color: rgb(17, 119, 0); }
.cm-s-inner .cm-attribute { color: rgb(0, 0, 204); }
.cm-s-inner .cm-header, .cm-s-inner.cm-header { color: rgb(0, 0, 255); }
.cm-s-inner .cm-quote, .cm-s-inner.cm-quote { color: rgb(0, 153, 0); }
.cm-s-inner .cm-hr, .cm-s-inner.cm-hr { color: rgb(153, 153, 153); }
.cm-s-inner .cm-link, .cm-s-inner.cm-link { color: rgb(0, 0, 204); }
.cm-negative { color: rgb(221, 68, 68); }
.cm-positive { color: rgb(34, 153, 34); }
.cm-header, .cm-strong { font-weight: 700; }
.cm-del { text-decoration: line-through; }
.cm-em { font-style: italic; }
.cm-link { text-decoration: underline; }
.cm-error { color: red; }
.cm-invalidchar { color: red; }
.cm-constant { color: rgb(38, 139, 210); }
.cm-defined { color: rgb(181, 137, 0); }
div.CodeMirror span.CodeMirror-matchingbracket { color: rgb(0, 255, 0); }
div.CodeMirror span.CodeMirror-nonmatchingbracket { color: rgb(255, 34, 34); }
.cm-s-inner .CodeMirror-activeline-background { background: inherit; }
.CodeMirror { position: relative; overflow: hidden; }
.CodeMirror-scroll { height: 100%; outline: 0px; position: relative; box-sizing: content-box; background: inherit; }
.CodeMirror-sizer { position: relative; }
.CodeMirror-gutter-filler, .CodeMirror-hscrollbar, .CodeMirror-scrollbar-filler, .CodeMirror-vscrollbar { position: absolute; z-index: 6; display: none; }
.CodeMirror-vscrollbar { right: 0px; top: 0px; overflow: hidden; }
.CodeMirror-hscrollbar { bottom: 0px; left: 0px; overflow: hidden; }
.CodeMirror-scrollbar-filler { right: 0px; bottom: 0px; }
.CodeMirror-gutter-filler { left: 0px; bottom: 0px; }
.CodeMirror-gutters { position: absolute; left: 0px; top: 0px; padding-bottom: 30px; z-index: 3; }
.CodeMirror-gutter { white-space: normal; height: 100%; box-sizing: content-box; padding-bottom: 30px; margin-bottom: -32px; display: inline-block; }
.CodeMirror-gutter-wrapper { position: absolute; z-index: 4; background: 0px 0px !important; border: none !important; }
.CodeMirror-gutter-background { position: absolute; top: 0px; bottom: 0px; z-index: 4; }
.CodeMirror-gutter-elt { position: absolute; cursor: default; z-index: 4; }
.CodeMirror-lines { cursor: text; }
.CodeMirror pre { border-radius: 0px; border-width: 0px; background: 0px 0px; font-family: inherit; font-size: inherit; margin: 0px; white-space: pre; overflow-wrap: normal; color: inherit; z-index: 2; position: relative; overflow: visible; }
.CodeMirror-wrap pre { overflow-wrap: break-word; white-space: pre-wrap; word-break: normal; }
.CodeMirror-code pre { border-right: 30px solid transparent; width: fit-content; }
.CodeMirror-wrap .CodeMirror-code pre { border-right: none; width: auto; }
.CodeMirror-linebackground { position: absolute; left: 0px; right: 0px; top: 0px; bottom: 0px; z-index: 0; }
.CodeMirror-linewidget { position: relative; z-index: 2; overflow: auto; }
.CodeMirror-wrap .CodeMirror-scroll { overflow-x: hidden; }
.CodeMirror-measure { position: absolute; width: 100%; height: 0px; overflow: hidden; visibility: hidden; }
.CodeMirror-measure pre { position: static; }
.CodeMirror div.CodeMirror-cursor { position: absolute; visibility: hidden; border-right: none; width: 0px; }
.CodeMirror div.CodeMirror-cursor { visibility: hidden; }
.CodeMirror-focused div.CodeMirror-cursor { visibility: inherit; }
.cm-searching { background: rgba(255, 255, 0, 0.4); }
@media print {
.CodeMirror div.CodeMirror-cursor { visibility: hidden; }
}
:root { --side-bar-bg-color: #fafafa; --control-text-color: #777; }
html { font-size: 16px; }
body { font-family: "Open Sans", "Clear Sans", "Helvetica Neue", Helvetica, Arial, sans-serif; color: rgb(51, 51, 51); line-height: 1.6; }
#write { max-width: 860px; margin: 0px auto; padding: 30px 30px 100px; }
#write > ul:first-child, #write > ol:first-child { margin-top: 30px; }
a { color: rgb(65, 131, 196); }
h1, h2, h3, h4, h5, h6 { position: relative; margin-top: 1rem; margin-bottom: 1rem; font-weight: bold; line-height: 1.4; cursor: text; }
h1:hover a.anchor, h2:hover a.anchor, h3:hover a.anchor, h4:hover a.anchor, h5:hover a.anchor, h6:hover a.anchor { text-decoration: none; }
h1 tt, h1 code { font-size: inherit; }
h2 tt, h2 code { font-size: inherit; }
h3 tt, h3 code { font-size: inherit; }
h4 tt, h4 code { font-size: inherit; }
h5 tt, h5 code { font-size: inherit; }
h6 tt, h6 code { font-size: inherit; }
h1 { padding-bottom: 0.3em; font-size: 2.25em; line-height: 1.2; border-bottom: 1px solid rgb(238, 238, 238); }
h2 { padding-bottom: 0.3em; font-size: 1.75em; line-height: 1.225; border-bottom: 1px solid rgb(238, 238, 238); }
h3 { font-size: 1.5em; line-height: 1.43; }
h4 { font-size: 1.25em; }
h5 { font-size: 1em; }
h6 { font-size: 1em; color: rgb(119, 119, 119); }
p, blockquote, ul, ol, dl, table { margin: 0.8em 0px; }
li > ol, li > ul { margin: 0px; }
hr { height: 2px; padding: 0px; margin: 16px 0px; background-color: rgb(231, 231, 231); border: 0px none; overflow: hidden; box-sizing: content-box; }
li p.first { display: inline-block; }
ul, ol { padding-left: 30px; }
ul:first-child, ol:first-child { margin-top: 0px; }
ul:last-child, ol:last-child { margin-bottom: 0px; }
blockquote { border-left: 4px solid rgb(223, 226, 229); padding: 0px 15px; color: rgb(119, 119, 119); }
blockquote blockquote { padding-right: 0px; }
table { padding: 0px; word-break: initial; }
table tr { border-top: 1px solid rgb(223, 226, 229); margin: 0px; padding: 0px; }
table tr:nth-child(2n), thead { background-color: rgb(248, 248, 248); }
table tr th { font-weight: bold; border-width: 1px 1px 0px; border-top-style: solid; border-right-style: solid; border-left-style: solid; border-top-color: rgb(223, 226, 229); border-right-color: rgb(223, 226, 229); border-left-color: rgb(223, 226, 229); border-image: initial; border-bottom-style: initial; border-bottom-color: initial; margin: 0px; padding: 6px 13px; }
table tr td { border: 1px solid rgb(223, 226, 229); margin: 0px; padding: 6px 13px; }
table tr th:first-child, table tr td:first-child { margin-top: 0px; }
table tr th:last-child, table tr td:last-child { margin-bottom: 0px; }
.CodeMirror-lines { padding-left: 4px; }
.code-tooltip { box-shadow: rgba(0, 28, 36, 0.3) 0px 1px 1px 0px; border-top: 1px solid rgb(238, 242, 242); }
.md-fences, code, tt { border: 1px solid rgb(231, 234, 237); background-color: rgb(248, 248, 248); border-radius: 3px; padding: 2px 4px 0px; font-size: 0.9em; }
code { background-color: rgb(243, 244, 244); padding: 0px 2px; }
.md-fences { margin-bottom: 15px; margin-top: 15px; padding-top: 8px; padding-bottom: 6px; }
.md-task-list-item > input { margin-left: -1.3em; }
@media print {
html { font-size: 13px; }
table, pre { break-inside: avoid; }
pre { overflow-wrap: break-word; }
}
.md-fences { background-color: rgb(248, 248, 248); }
#write pre.md-meta-block { padding: 1rem; font-size: 85%; line-height: 1.45; background-color: rgb(247, 247, 247); border: 0px; border-radius: 3px; color: rgb(119, 119, 119); margin-top: 0px !important; }
.mathjax-block > .code-tooltip { bottom: 0.375rem; }
.md-mathjax-midline { background: rgb(250, 250, 250); }
#write > h3.md-focus::before { left: -1.5625rem; top: 0.375rem; }
#write > h4.md-focus::before { left: -1.5625rem; top: 0.285714rem; }
#write > h5.md-focus::before { left: -1.5625rem; top: 0.285714rem; }
#write > h6.md-focus::before { left: -1.5625rem; top: 0.285714rem; }
.md-image > .md-meta { border-radius: 3px; padding: 2px 0px 0px 4px; font-size: 0.9em; color: inherit; }
.md-tag { color: rgb(167, 167, 167); opacity: 1; }
.md-toc { margin-top: 20px; padding-bottom: 20px; }
.sidebar-tabs { border-bottom: none; }
#typora-quick-open { border: 1px solid rgb(221, 221, 221); background-color: rgb(248, 248, 248); }
#typora-quick-open-item { background-color: rgb(250, 250, 250); border-color: rgb(254, 254, 254) rgb(229, 229, 229) rgb(229, 229, 229) rgb(238, 238, 238); border-style: solid; border-width: 1px; }
.on-focus-mode blockquote { border-left-color: rgba(85, 85, 85, 0.12); }
header, .context-menu, .megamenu-content, footer { font-family: "Segoe UI", Arial, sans-serif; }
.file-node-content:hover .file-node-icon, .file-node-content:hover .file-node-open-state { visibility: visible; }
.mac-seamless-mode #typora-sidebar { background-color: var(--side-bar-bg-color); }
.md-lang { color: rgb(180, 101, 77); }
.html-for-mac .context-menu { --item-hover-bg-color: #E6F0FE; }
#md-notification .btn { border: 0px; }
.dropdown-menu .divider { border-color: rgb(229, 229, 229); }
.ty-preferences .window-content { background-color: rgb(250, 250, 250); }
.ty-preferences .nav-group-item.active { color: white; background: rgb(153, 153, 153); }
-->
Python学习day25-面向对象之小结
面向对象解决的问题
面向对象的编程是一种思想，主要就是用于区别面向过程这种思想。其解决的最大的问题就是程序的扩展性，因为面向过程的编程扩展起来非常的麻烦，所以才产生了面向对象这种编程思想，但编程思想并没有高低之分，并不是说我们以后所有的程序都要用面向对象的思想来完成，这是非常偏激的做法，我们应该在适当的时候选择是用面向对象还是面向过程的方法。
面向对象的编程固然解决了程序的可扩展性，但他也有其缺点，代码量大，结构构思较难等，都是真实存在的，所以根据现实情况选择最适合的编程方式才是最正确的。
类与对象
类：是一系列共同的属性和方法
对象：是属性和方法的结合体
现实生活中是先有对象，才有总结的类，但在Python中，我们要先定义类，然后派生或者说实例化产生对象。
类及对象的定义
具体实例见https://www.cnblogs.com/Xu-PR/p/11412865.html
绑定方法及非绑定方法
绑定方法的意思就是，绑定谁就给谁来用，并且会把自身作为第一个参数传进方法里去，绑定方法分为对象的绑定方法以及类的绑定方法。
非绑定方法就与之相反，即不管是对象还是类都可以调用，且不必把自己传进去作为第一个参数，实际上非绑定方法就是定义在类内部，但是就是一个普通的方法，谁都不绑定，另外，非绑定方法又叫静态方法。
绑定方法用到的装饰器是classmethod，非绑定方法用到的装饰器是staticmethod，实例如下：
xxxxxxxxxx
class Person:
'''
注释的内容
'''
def __init__(self, name, age):
self.name = name
self.age = age
def func(self):
print('对象的绑定方法')
@classmethod
def class_method(cls):
print('我是类的绑定方法，类调用')
# 当成一个普通函数，只不过是写在类内部的，非绑定方法，也叫静态方法
@staticmethod
def static_method():
print('静态方法，谁都不绑定')
# 绑定到对象的方法
u = Person('nick', 19)
u.def()
# 绑定到类的方法
Person.class_method()
# 静态方法调用：
# 类来调用
Person.static_method()
# 对象来调用
p = Person('nick', 19)
p.static_method()
一般情况下，当一个方法跟类和对象都没有关系的时候，会考虑将其定义成静态方法，一般在类内部使用，当然类外部也可以使用，不过不推荐。
面向对象三大特征
继承
继承的概念
继承是一种新建类的方式，继承一个类，那么类中的属性和方法在子类中都可以使用，被继承的类叫做父类（基类），继承的类叫做子类（派生类）。继承最大的作用是减少代码量，
继承过的类分两种，即新式类和经典类，新式类是指继承了object的类，在Python3中默认都是新式类，但没有继承object的类叫做经典类，在Python2中存在，Python2中如果需要定义新式类的话就必须在括号里加上object，否则生成的就是经典类。
新式类和经典类的区别不太大，但还是有区别，最主要的区别体现在属性的查找顺序上，且只有菱形问题才有区别。菱形问题就是一个文件中所有的类都显示的继承一个类，就是大家集成到最后发现继承的都是同一个类，那么新式类和经典类的属性查找顺序就会有问题。
新式类主要是以广度优先的方式来查找属性，或者方法，即从左向右，每次往上寻找，但不找到顶点，直到最后一条继承线找完才会寻找最后一个顶点。
经典类与新式类的区别则是以深度优先的方式来查找属性，即从左开始第一条继承线就会寻找到最后顶点，然后继续向右寻找。代码及示意图如下：
xxxxxxxxxx
class A(object):
def test(self):
print('from A')
class B(A):
def test(self):
print('from B')
class C(A):
def test(self):
print('from C')
class D(B):
def test(self):
print('from D')
class E(C):
def test(self):
print('from E')
class F(D,E):
# def test(self):
# print('from F')
pass
f1=F()
f1.test()
print(F.__mro__) #只有新式才有这个属性可以查看线性列表，经典类没有这个属性
重用父类的两个方法
- 指名道姓式，即直接用
父类名.方法/属性的方式来重用父类的方法 - super()关键字，相当于父类名()，其查找顺序严格按照mro的列表查找
多态和多态性
多态就是一类事物的多种形态，比如动物类的猪，狗，鹿。多态增加了程序的灵活性，同时也增加了程序的可扩展性。
其实多态有时候在程序里并不是一件特别好的事情，因为项目很大的情况下，每个人分工合作，变量以及用的方法很容易名字造成冲突，所以我们要对子类的方法进行约束，让其实现父类的方法。
这里推荐两种方法：
- abc模块
- 抛异常
具体的代码示例前面博客已经写过，不再赘述。
封装
组合也是封装的一种，也就是把一些东西隐藏起来，起到保护，和隔离复杂度的作用。
Python里隐藏的方法是属性或方法前面加__，注意后面不要加，因为这不是内置属性。其中隐藏属性的目的是为了数据的安全，隐藏方法的目的则是隔离复杂度，让使用者只需要了解自己用到的方法及作用就可以了，不必了解内部用的什么原理，或者调用了多少方法。
面向对象的三个常用装饰器
其实可以说是一个装饰器，就是property，另外的setter和deleter都是依附于property存在的。
xxxxxxxxxx
class Person:
def __init__(self, name, height, weight):
self.__name = name
self.__height = height
self.__weight = weight
@property# 可以把方法封装成数据属性，即使用者调用该方法的时候会认为这是一个固定的属性，而不是一个方法这里封装的方法是name，所以下面setter和deleter调用时候都是name调用的
def name(self):
return self.__name
# 用property装饰的方法名.setter
@name.setter # setter是和property组合使用，用以修改被property装饰过的方法
def name(self, new_name):
# if not isinstance(new_name, str): # 判断第一个对象是否是某个类的对象
if type(new_name) is not str:
raise Exception('不能修改')
else:
self.__name = new_name
@name.deleter # 和property组合使用，用以删除被装饰的隐藏值，少用，或者不用
def name(self):
# raise Exception('不能删除')
print('删除成功')
# del self.__name
p = Person('lqz', 1.8, 70)
p.name = 99
print(p.name)