import extends useinclude语句包含入一个模板并在当前命名空间返回其渲染的

¶ statementincludesatemteandreturnstherenderedcontentofthatfileintothecurrentIncludedtemteshaveaccesstothevariablesoftheactiveIfyouareusingthefilesystemloader,thetemtesarelookedforinthepathsdefinedbyYoucanaddadditionalvariablesbypassingthemafter Youcandisableaccesstothecontextbyappending Whenincludingatemtecreatedbyanenduser,youshouldconsidersandboxingit.MoreinformationintheTwigforDeveloperschapterandinthesandboxtagation.的TwigforDevelopers的sandboxThetemtenamecanbeanyvalidTwigAndiftheexpressionevaluatesto object,TwigwilluseitNewinversion1.2:ThefeaturehasbeenaddedinTwigYoucanmarkanincludewithinwhichcaseTwigwillignorethestatementifthetemtetobeincludeddoesnotexist.Ithastobecedjustafterthetemtename.Heresomevalidexamples:你可以用ignoremissing标记一个include，这样Twig将忽略此模板不存在的情况。这个参数直接加到模板名后Newinversion1.2:ThepossibilitytopassanarrayoftemteshasbeenaddedinTwigYoucanalsoprovidealistoftemtesthatarecheckedforexistencebeforeinclusion.Thefirsttemtethatexistswillbeincluded:Ifisgiven,itwillfallbacktorenderingnothingifnoneofthetemtesexist,otherwiseitwillthrowanexception. ¶Twigsupportsputtingoftenusedcodeintomacros.Thesemacroscangointodifferenttemtesandgetimportedfromthere.Therearetwowaystoimporttemtes.Youcanimportthecompletetemteintoavariableorrequestspecificmacrosfromit.Imaginewehaveahelpermodulethatrendersforms 想象一下我们有一个渲染表单的协助器模块（叫forms.html）:Theeasiestandmostflexibleisimportingthewholemoduleintoavariable.ThatwayyoucanaccesstheAlternativelyyoucanimportnamesfromthetemteintothecurrentToimportmacrosfromthecurrentfile,usethe variableforthe¶ tagcanbeusedtoextendatemtefromanotherLikePHP,Twigdoesnotsupportmultipleinheritance.Soyoucanonlyhaveoneextendstagcalledperrendering.However,Twigsupportshorizontalreuse.,Let'sdefineabasetem ,whichdefinesasimpleHTMLskeletonInthisexample,theblocktagsdefinefourblocksthatchildtemtescanfillAllthe tagdoesisto lthetemteenginethatachildtemtemayoverridethoseportionsoftheChild Achildtemtemightlooklike tagisthekeyhere.Itlsthetemteenginethatthistemte"extends"anothertemte.Whenthetemtesystemevaluatesthistemte,firstitlocatestheparent.Theextendstagshouldbethefirsttaginthetemte.Notethatsincethechildtemtedoesn'tdefinethe block,thevaluefromtheparenttemteisusedinstead.Youcan'tdefinemultiple tagswiththesamenameinthesametemte.Thislimitationexistsbecauseablocktagworksin"both"directions.Thatis,ablocktagdoesn'tjustprovideaholetofill-italsodefinesthecontentthatfillstheholeintheparent.Ifthereweretwo tagsinatemte,thattemte'sparentwouldn'tknowwhichoneoftheblocks'contenttouse.Ifyouwanttoprintablockmultipletimesyoucanhoweveruse 首先它定位父模板。extends应该模板里的顶一个。你不能在同一个模板里给多个block同一个名称。这个限制条件的存在是因为一个block可以“双向”工作。一个block不仅是提供一个洞去填充，它也是定义填充父模板的内容。如果一个模板里有两个类似名ParentIt'spossibletorenderthecontentsoftheparentblockbyusingtheparentfunction.Thisgivesbacktheresultsoftheparentblock:NamedBlockEnd-TwigallowsyoutoputthenameoftheblockaftertheendtagforbetterOfcourse,thenameafter wordmustmatchtheblockBlockNestingandBlockscanbenestedformorecomplexlayouts.Perdefault,blockshaveaccesstovariablesfromouter当然，endblock里的名称必须和blockname相符。BlockForblockswithfewcontent,it'spossibletouseashortcutsyntax.ThefollowingconstructsdotheDynamicTwigsupportsdynamicinheritancebyusingavariableasthebasetemIfthevariableevaluatesto object,TwigwilluseitastheparenttemNewinversion1.2:ThepossibilitytopassanarrayoftemteshasbeenaddedinTwigYoucanalsoprovidealistoftemtesthatarecheckedforexistence.Thefirsttemtethatexistswillbeusedasaparent:AsthetemtenamefortheparentcanbeanyvalidTwigexpression,it'spossibletomaketheinheritancemechanismconditional:Inthisexample,thetemtewillextendthe"minimum.html"layouttemteifthevariableevaluatesto ,and"base.html"otherwise.Howdoblockswork?Ablockprovidesawaytochangehowacertainpartofatemteisrenderedbutitdoesnotinterfereinanywaywiththelogicaroundit.Let'stakethefollowingexampletoillustratehowablockworksandmoreimportantly,howitdoesnotwork:在这个例子里，如果变量tandalone变量是true模板将扩展“minimum.html”扩展“bas.html”block提供法修改一个模板的确定部分怎样渲染，但它不涉及任何逻辑。让我们用下边的例子说明一个block112345678{#base.twig{%forpostinposts{%blockpost<h1>{{post.title<p>{{post.body{%endblock{%endforIfyourenderthistemte,theresultwouldbeexactlythesamewithorwithoutthe insidethe loopisjustawaytomakeitoverridablebyachildtemte:如果你渲染这个模板，结构将确切的会是同样有或者没有lock。在for循环里的block是一种让子模板覆盖的方法：1123456789{#child.twig{%extends"base.twig"{%blockpost<header>{{post.title<section>{{post.text{%endblockNow,whenrenderingthechildtemte,theloopisgoingtousetheblockdefinedinthechildtemteinsteadoftheonedefinedinthebaseone;theexecutedtemteisthenequivalenttothefollowingone:现在，当渲染子模板，循环会使用子模板定义的lock{%{%forpostinposts<header>{{post.title<section>{{post.text{%endforLet'stakeanotherexample:ablockincludedwithin 11234567{%ifpostsisempty{%blockhead{{parent()<metaname="robots"content="noindex,{%endblockhead{%endifContrarytowhatyoumightthink,thistemtedoesnotdefineablockconditionally;itjustmakesoverridablebyachildtemtetheoutputofwhatwillberenderedwhenthecondition Ifyouwanttheoutputtobedisyedconditionally,usethefollowing或许和你相反，这个模板没定义一个block条件，当条件是true时它仅仅由子模板覆盖将 {%blockhead{{parent()4423{%ifpostsisempty<metaname="robots"content="noindex,{%endif{%endblockhead567¶Newinversion1.1:HorizontalreusewasaddedinTwigHorizontalreuseisanadvancedTwigfeaturethatishardlyeverneededintemtes.Itismainlyusedbyprojectsthatneedtomaketemteblocksreusablewithoutusinginheritance.TemteinheritanceisoneofthemostpowerfulTwig'sfeaturebutitislimitedtosingleinheritance;atemtecanonlyextendoneothertemte.Thislimitationmakestemteinheritancesimpletounderstandandeasytodebug:Horizontalreuseisawaytoachievethesamegoalasmultipleinheritance,butwithouttheassociated lsTwigtoimporttheblocksdefinedin intothecurrenttemte(it'slikemacros,butforblocks):Inthisexample,the statementimportsthe blockintothemaintemte.Thecodeismostlyequivalenttothefollowingone(theimportedblocksarenotoutputtedautomatically): tagonlyimportsatemteifitdoesnotextendanothertemte,ifitdoesnotdefinemacros,andifthebodyisempty.Butitcanuseothertemtes. statementsareresolvedindependentlyofthecon