98 lines
2.9 KiB
Objective-C
98 lines
2.9 KiB
Objective-C
/////////////////////////////////////////////////////////////////////////////
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// Name: recguard.h
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// Purpose: interface of wxRecursionGuardFlag
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// Author: wxWidgets team
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// Licence: wxWindows licence
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/////////////////////////////////////////////////////////////////////////////
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/**
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@class wxRecursionGuardFlag
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This is a completely opaque class which exists only to be used with
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wxRecursionGuard, please see the example in that class' documentation.
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@remarks
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wxRecursionGuardFlag object must be declared @c static or the recursion
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would never be detected.
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@library{wxbase}
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@category{misc}
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*/
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class wxRecursionGuardFlag
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{
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public:
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};
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/**
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@class 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
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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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wxRecursionGuardFlag like in this example:
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@code
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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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@endcode
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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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IsInside() 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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@library{wxbase}
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@category{misc}
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*/
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class wxRecursionGuard
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{
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public:
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/**
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A wxRecursionGuard object must always be initialized with a @c static
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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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IsInside().
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*/
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wxRecursionGuard(wxRecursionGuardFlag& flag);
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/**
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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 This is not virtual, so this class is not meant to be derived
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from (besides, there is absolutely no reason to do it anyhow).
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*/
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~wxRecursionGuard();
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/**
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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).
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Usually the function using wxRecursionGuard takes some specific actions
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in such case (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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*/
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bool IsInside() const;
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};
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