📄 3.3.htm
字号:
align=absMiddle border=0></A></TD></TR></TBODY></TABLE>
<HR SIZE=1>
<TABLE cellSpacing=0 cellPadding=5 width="100%" border=0>
<TBODY>
<TR>
<TD vAlign=top width=67 rowSpan=3><IMG
src="3.3.files/ruby_xs.gif" width=67 border=0></TD>
<TD class=v2 vAlign=top><A class=v1
href="http://proquest.safaribooksonline.com/JVXSL.asp?x=1&mode=section&sortKey=title&sortOrder=asc&view=&xmlid=0-59600-214-9&open=false&catid=&s=1&b=1&f=1&t=0&c=1&u=1&srchText=">Ruby
in a Nutshell</A><BR>By Yukihiro Matsumoto<BR></TD></TR>
<TR>
<TD class=v2> </TD></TR>
<TR>
<TD class=t1 vAlign=bottom>Chapter 3. Built-in Library
Reference</TD></TR></TBODY></TABLE>
<HR SIZE=1>
<BR>
<TABLE cellSpacing=0 cellPadding=0 width="100%" border=0>
<TBODY>
<TR>
<TD vAlign=top><A name=ruby-CHP-3-SECT-3></A>
<H3 class=docSection1Title>3.3 Built-in Functions</H3><A
name=ruby-IDXTERM-507></A>
<P class=docText><A name=IXT-3-127254></A><A
name=IXT-3-127255></A>Since the <TT>Kernel</TT> module is
included by <TT>Object</TT> class, its methods are available
everywhere in the Ruby program. They can be called without a
receiver (functional form), therefore, they are often called
<SPAN class=docEmphasis>functions</SPAN>. </P><A
name=IXT-3-127256></A><A name=IXT-3-127257></A><A
name=IXT-3-127258></A><A name=IXT-3-127259></A><A
name=IXT-3-127260></A><A name=IXT-3-127261></A><A
name=IXT-3-127262></A><A name=IXT-3-127263></A><A
name=IXT-3-127264></A><A name=IXT-3-127265></A><A
name=IXT-3-127266></A><A name=IXT-3-127267></A><A
name=IXT-3-127268></A><A name=IXT-3-127269></A><A
name=IXT-3-127270></A><A name=IXT-3-127271></A><A
name=IXT-3-127272></A><A name=IXT-3-127273></A><A
name=IXT-3-127274></A><A name=IXT-3-127275></A><A
name=IXT-3-127276></A><A name=IXT-3-127277></A><A
name=IXT-3-127278></A><A name=IXT-3-127279></A><A
name=IXT-3-127280></A><A name=IXT-3-127281></A><A
name=IXT-3-127282></A><A name=IXT-3-127283></A><A
name=IXT-3-127284></A><A name=IXT-3-127285></A><A
name=IXT-3-127286></A><A name=IXT-3-127287></A><A
name=IXT-3-127288></A><A name=IXT-3-127289></A><A
name=IXT-3-127290></A><A name=IXT-3-127291></A><A
name=IXT-3-127292></A><A name=IXT-3-127293></A><A
name=IXT-3-127294></A><A name=IXT-3-127295></A><A
name=IXT-3-127296></A><A name=IXT-3-127297></A><A
name=IXT-3-127298></A><A name=IXT-3-127299></A><A
name=IXT-3-127300></A><A name=IXT-3-127301></A><A
name=IXT-3-127302></A><A name=IXT-3-127303></A><A
name=IXT-3-127304></A><A name=IXT-3-127305></A><A
name=IXT-3-127306></A><A name=IXT-3-127307></A><A
name=IXT-3-127308></A><A name=IXT-3-127309></A><A
name=IXT-3-127310></A><A name=IXT-3-127311></A><A
name=IXT-3-127312></A><A name=IXT-3-127313></A><A
name=IXT-3-127314></A><A name=IXT-3-127315></A><A
name=IXT-3-127316></A><A name=IXT-3-127317></A><A
name=IXT-3-127318></A><A name=IXT-3-127319></A><A
name=IXT-3-127320></A><A name=IXT-3-127321></A><A
name=IXT-3-127322></A><A name=IXT-3-127323></A><A
name=IXT-3-127324></A><A name=IXT-3-127325></A><A
name=IXT-3-127326></A><A name=IXT-3-127327></A><A
name=IXT-3-127328></A><A name=IXT-3-127329></A><A
name=IXT-3-127330></A><A name=IXT-3-127331></A><A
name=IXT-3-127332></A><A name=IXT-3-127333></A><A
name=IXT-3-127334></A><A name=IXT-3-127335></A><A
name=IXT-3-127336></A><A name=IXT-3-127337></A><A
name=IXT-3-127338></A><A name=IXT-3-127339></A><A
name=IXT-3-127340></A><A name=IXT-3-127341></A><A
name=IXT-3-127342></A><A name=IXT-3-127343></A><A
name=IXT-3-127344></A><A name=IXT-3-127345></A><A
name=IXT-3-127346></A><A name=IXT-3-127347></A><A
name=IXT-3-127348></A><A name=IXT-3-127349></A><A
name=IXT-3-127350></A><A name=IXT-3-127351></A><A
name=IXT-3-127352></A><A name=IXT-3-127353></A><A
name=IXT-3-127354></A><A name=IXT-3-127355></A><A
name=IXT-3-127356></A><A name=IXT-3-127357></A><A
name=IXT-3-127358></A><A name=IXT-3-127359></A><A
name=IXT-3-127360></A><A name=IXT-3-127361></A><A
name=IXT-3-127362></A><A name=IXT-3-127363></A><A
name=IXT-3-127364></A><A name=IXT-3-127365></A><A
name=IXT-3-127366></A><A name=IXT-3-127367></A><A
name=IXT-3-127368></A><A name=IXT-3-127369></A><A
name=IXT-3-127370></A><A name=IXT-3-127371></A><A
name=IXT-3-127372></A><A name=IXT-3-127373></A><A
name=IXT-3-127374></A><A name=IXT-3-127375></A><A
name=IXT-3-127376></A><A name=IXT-3-127377></A><A
name=IXT-3-127378></A><A name=IXT-3-127379></A><A
name=IXT-3-127380></A><A name=IXT-3-127381></A><A
name=IXT-3-127382></A><A name=IXT-3-127383></A><A
name=IXT-3-127384></A><A name=IXT-3-127385></A><A
name=IXT-3-127386></A><A name=IXT-3-127387></A><A
name=IXT-3-127388></A><A name=IXT-3-127389></A><A
name=IXT-3-127390></A><A name=IXTR3-12></A>
<DL class=docList><A name=IXT-3-127256></A>
<DT><SPAN class=docPubcolor><SPAN class=docPubcolor><SPAN
class=docMonofont>abort</SPAN></SPAN></SPAN>
<DD>
<P class=docList>Terminates program. If an exception is
raised (i.e., <TT>$!</TT> isn't <TT>nil</TT>), its error
message is displayed. </P><A name=IXT-3-127257></A>
<DT><SPAN class=docPubcolor><SPAN class=docPubcolor><SPAN
class=docMonofont>Array(</SPAN></SPAN>
<TT><I>obj</I></TT><SPAN class=docPubcolor><SPAN
class=docMonofont>)</SPAN></SPAN> </SPAN>
<DD>
<P class=docList>Returns <TT><I>obj</I></TT> after
converting it to an array using <TT>to_ary</TT> or
<TT>to_a</TT>. </P><A name=IXT-3-127258></A><A
name=IXT-3-127259></A>
<DT><SPAN class=docPubcolor><SPAN class=docPubcolor><SPAN
class=docMonofont>at_exit {...}</SPAN></SPAN></SPAN>
<DD>
<P class=docList>Registers a block for execution when the
program exits. Similar to <TT>END</TT> statement (referenced
in <A class=docLink
href="http://proquest.safaribooksonline.com/JVXSL.asp?xmlid=0-59600-214-9/ruby-CHP-2-SECT-8#ruby-CHP-2-SECT-8">Section
2.8</A>), but <TT>END</TT> statement registers the block
only once. </P><A name=IXT-3-127260></A>
<DT><SPAN class=docPubcolor><SPAN class=docPubcolor><SPAN
class=docMonofont>autoload(</SPAN></SPAN>
<TT><I>classname</I></TT><SPAN class=docPubcolor><SPAN
class=docMonofont>,</SPAN></SPAN> <TT><I>file</I></TT><SPAN
class=docPubcolor><SPAN class=docMonofont>)</SPAN></SPAN>
</SPAN>
<DD>
<P class=docList>Registers a class <TT><I>classname</I></TT>
to be loaded from file the first time it's used.
<TT><I>classname</I></TT> may be a string or a symbol. </P><PRE>autoload :Foo, "foolib.rb".</PRE><A
name=IXT-3-127261></A>
<DT><SPAN class=docPubcolor><SPAN class=docPubcolor><SPAN
class=docMonofont>binding</SPAN></SPAN></SPAN>
<DD>
<P class=docList>Returns the current variable and method
bindings. The <TT>Binding</TT> object that is returned may
be passed to the <TT>eval</TT> method as its second
argument. </P><A name=IXT-3-127262></A><A
name=IXT-3-127263></A>
<DT><SPAN class=docPubcolor><SPAN class=docPubcolor><SPAN
class=docMonofont>block_given?</SPAN></SPAN></SPAN>
<DD>
<P class=docList>Returns <TT>true</TT> if the method was
called with a block.</P><A name=IXT-3-127264></A><A
name=IXT-3-127265></A>
<DT><SPAN class=docPubcolor><SPAN class=docPubcolor><SPAN
class=docMonofont>callcc {|</SPAN></SPAN>
<TT><I>c</I></TT><SPAN class=docPubcolor><SPAN
class=docMonofont>|...}</SPAN></SPAN> </SPAN>
<DD>
<P class=docList>Passes a <TT>Continuation</TT> object
<TT><I>c</I></TT> to the block and executes the block.
<TT>callcc</TT> can be used for global exit or loop
construct. </P><PRE>def foo(c)
puts "in foo" #
c.call # jump out
puts "out foo" # this line never be executed
end
callcc{|c| foo(c)} # prints "in foo"</PRE><A
name=IXT-3-127266></A>
<DT><SPAN class=docPubcolor><SPAN class=docPubcolor><SPAN
class=docMonofont>caller([</SPAN></SPAN>
<TT><I>n</I></TT><SPAN class=docPubcolor><SPAN
class=docMonofont>])</SPAN></SPAN> </SPAN>
<DD>
<P class=docList>Returns the current execution stack in an
array of the strings in the form
<TT><I>file</I></TT><TT>:</TT><TT><I>line</I></TT>. If
<TT><I>n</I></TT> is specified, returns stack entries from
<TT><I>n</I></TT>th level on down. </P><A
name=IXT-3-127267></A>
<DT><SPAN class=docPubcolor><SPAN class=docPubcolor><SPAN
class=docMonofont>catch(</SPAN></SPAN>
<TT><I>tag</I></TT><SPAN class=docPubcolor><SPAN
class=docMonofont>) {...}</SPAN></SPAN> </SPAN>
<DD>
<P class=docList>Catches a nonlocal exit by a throw called
during the execution of its block. </P><PRE>def throwing(n)
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -