fc2171bd4c
git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@27090 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
106 lines
3.3 KiB
TeX
106 lines
3.3 KiB
TeX
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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%% Name: recguard.tex
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%% Purpose: wxRecursionGuard documentation
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%% Author: Vadim Zeitlin
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%% Modified by:
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%% Created: 14.08.03
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%% RCS-ID: $Id$
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%% Copyright: (c) Vadim Zeitlin
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%% License: wxWidgets license
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%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
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\section{\class{wxRecursionGuard}}\label{wxrecursionguard}
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wxRecursionGuard is a very simple class which can be used to prevent reentrancy
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problems in a function. It is not thread-safe and so should be used only in the
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single-threaded programs or in combination with some thread synchronization
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mechanisms.
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wxRecursionGuard is always used together with the
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\helpref{wxRecursionGuardFlag}{wxrecursionguardflag} like in this example:
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\begin{verbatim}
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void Foo()
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{
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static wxRecursionGuardFlag s_flag;
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wxRecursionGuard guard(s_flag);
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if ( guard.IsInside() )
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{
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// don't allow reentrancy
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return;
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}
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...
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}
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\end{verbatim}
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As you can see, wxRecursionGuard simply tests the flag value and sets it to
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true if it hadn't been already set.
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\helpref{IsInside()}{wxrecursionguardisinside} allows testing the old flag
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value. The advantage of using this class compared to directly manipulating the
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flag is that the flag is always reset in the wxRecursionGuard destructor and so
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you don't risk to forget to do it even if the function returns in an unexpected
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way (for example because an exception has been thrown).
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\wxheading{Derived from}
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No base class
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\wxheading{Include files}
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<wx/recguard.h>
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\latexignore{\rtfignore{\wxheading{Members}}}
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\membersection{wxRecursionGuard::wxRecursionGuard}\label{wxrecursionguardctor}
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\func{}{wxRecursionGuard}{\param{wxRecursionGuardFlag\& }{flag}}
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A wxRecursionGuard object must always be initialized with a (static)
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\helpref{wxRecursionGuardFlag}{wxrecursionguardflag}. The constructor saves the
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value of the flag to be able to return the correct value from
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\helpref{IsInside}{wxrecursionguardisinside}.
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\membersection{wxRecursionGuard::\destruct{wxRecursionGuard}}\label{wxrecursionguarddtor}
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\func{}{\destruct{wxRecursionGuard}}{\void}
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The destructor resets the flag value so that the function can be entered again
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the next time.
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Note that it is not virtual and so this class is not meant to be derived from
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(besides, there is absolutely no reason to do it anyhow).
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\membersection{wxRecursionGuard::IsInside}\label{wxrecursionguardisinside}
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\constfunc{bool}{IsInside}{\void}
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Returns \true if we're already inside the code block ``protected'' by this
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wxRecursionGuard (i.e. between this line and the end of current scope). Usually
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the function using wxRecursionGuard takes some specific actions in such case
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(may be simply returning) to prevent reentrant calls to itself.
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If this method returns \false, it is safe to continue.
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\section{\class{wxRecursionGuardFlag}}\label{wxrecursionguardflag}
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This is a completely opaque class which exists only to be used with
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\helpref{wxRecursionGuard}{wxrecursionguard}, please see the example in that
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class documentation.
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Please notice that wxRecursionGuardFlag object \emph{must} be declared
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\texttt{static} or the recursion would never be detected.
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\wxheading{Derived from}
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No base class
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\wxheading{Include files}
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<wx/recguard.h>
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