cpl__error_8h.html

gdal库的学习文档

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Report an error.<p>
This function reports an error in a manner that can be hooked and reported appropriate by different applications.<p>
The effect of this function can be altered by applications by installing a custom error handling using <a class="el" href="cpl__error_8h.html#74d0e649d58180e621540bf73b58e4a2">CPLSetErrorHandler()</a>.<p>
The eErrClass argument can have the value CE_Warning indicating that the message is an informational warning, CE_Failure indicating that the action failed, but that normal recover mechanisms will be used or CE_Fatal meaning that a fatal error has occured, and that <a class="el" href="cpl__error_8h.html#ad2b98dd58e4de706a245faddac90403">CPLError()</a> should not return.<p>
The default behaviour of <a class="el" href="cpl__error_8h.html#ad2b98dd58e4de706a245faddac90403">CPLError()</a> is to report errors to stderr, and to abort() after reporting a CE_Fatal error. It is expected that some applications will want to supress error reporting, and will want to install a C++ exception, or longjmp() approach to no local fatal error recovery.<p>
Regardless of how application error handlers or the default error handler choose to handle an error, the error number, and message will be stored for recovery with <a class="el" href="cpl__error_8h.html#198afe56aced1d73226880aa90d39b99">CPLGetLastErrorNo()</a> and <a class="el" href="cpl__error_8h.html#7f71ade3bb0a0e9e45802975ec59ff5e">CPLGetLastErrorMsg()</a>.<p>
<dl compact><dt><b>Parameters:</b></dt><dd>
  <table border="0" cellspacing="2" cellpadding="0">
    <tr><td valign="top"></td><td valign="top"><em>eErrClass</em>&nbsp;</td><td>one of CE_Warning, CE_Failure or CE_Fatal. </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>err_no</em>&nbsp;</td><td>the error number (CPLE_*) from <a class="el" href="cpl__error_8h.html">cpl_error.h</a>. </td></tr>
    <tr><td valign="top"></td><td valign="top"><em>fmt</em>&nbsp;</td><td>a printf() style format string. Any additional arguments will be treated as arguments to fill in this format in a manner similar to printf(). </td></tr>
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<a class="anchor" name="29626fd8fdb658b19439beeb73a59560"></a><!-- doxytag: member="cpl_error.h::CPLErrorReset" ref="29626fd8fdb658b19439beeb73a59560" args="(void)" -->
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          <td class="memname">void CPLErrorReset           </td>
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<p>
Erase any traces of previous errors.<p>
This is normally used to ensure that an error which has been recovered from does not appear to be still in play with high level functions. 
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Get the last error message.<p>
Fetches the last error message posted with <a class="el" href="cpl__error_8h.html#ad2b98dd58e4de706a245faddac90403">CPLError()</a>, that hasn't been cleared by <a class="el" href="cpl__error_8h.html#29626fd8fdb658b19439beeb73a59560">CPLErrorReset()</a>. The returned pointer is to an internal string that should not be altered or freed.<p>
<dl class="return" compact><dt><b>Returns:</b></dt><dd>the last error message, or NULL if there is no posted error message. </dd></dl>

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<a class="anchor" name="198afe56aced1d73226880aa90d39b99"></a><!-- doxytag: member="cpl_error.h::CPLGetLastErrorNo" ref="198afe56aced1d73226880aa90d39b99" args="(void)" -->
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Fetch the last error number.<p>
This is the error number, not the error class.<p>
<dl class="return" compact><dt><b>Returns:</b></dt><dd>the error number of the last error to occur, or CPLE_None (0) if there are no posted errors. </dd></dl>

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<a class="anchor" name="8df0d4e01034cf79202314c92251e920"></a><!-- doxytag: member="cpl_error.h::CPLGetLastErrorType" ref="8df0d4e01034cf79202314c92251e920" args="(void)" -->
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          <td class="memname">CPLErr CPLGetLastErrorType           </td>
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<p>
Fetch the last error type.<p>
This is the error class, not the error number.<p>
<dl class="return" compact><dt><b>Returns:</b></dt><dd>the error number of the last error to occur, or CE_None (0) if there are no posted errors. </dd></dl>

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<a class="anchor" name="c6c7c393c94b210e4be999f34fcb6680"></a><!-- doxytag: member="cpl_error.h::CPLPopErrorHandler" ref="c6c7c393c94b210e4be999f34fcb6680" args="(void)" -->
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          <td class="memname">void CPLPopErrorHandler           </td>
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<p>
Pop error handler off stack.<p>
Discards the current error handler on the error handler stack, and restores the one in use before the last <a class="el" href="cpl__error_8h.html#d13c9c8f2037ddfd566c2a197f7b2537">CPLPushErrorHandler()</a> call. This method has no effect if there are no error handlers on the current threads error handler stack. 
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<a class="anchor" name="d13c9c8f2037ddfd566c2a197f7b2537"></a><!-- doxytag: member="cpl_error.h::CPLPushErrorHandler" ref="d13c9c8f2037ddfd566c2a197f7b2537" args="(CPLErrorHandler)" -->
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          <td class="memname">void CPLPushErrorHandler           </td>
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<p>
Push a new CPLError handler.<p>
This pushes a new error handler on the thread-local error handler stack. This handler will be used untill removed with <a class="el" href="cpl__error_8h.html#c6c7c393c94b210e4be999f34fcb6680">CPLPopErrorHandler()</a>.<p>
The <a class="el" href="cpl__error_8h.html#74d0e649d58180e621540bf73b58e4a2">CPLSetErrorHandler()</a> docs have further information on how CPLError handlers work.<p>
<dl compact><dt><b>Parameters:</b></dt><dd>
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    <tr><td valign="top"></td><td valign="top"><em>pfnErrorHandlerNew</em>&nbsp;</td><td>new error handler function. </td></tr>
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<a class="anchor" name="74d0e649d58180e621540bf73b58e4a2"></a><!-- doxytag: member="cpl_error.h::CPLSetErrorHandler" ref="74d0e649d58180e621540bf73b58e4a2" args="(CPLErrorHandler)" -->
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<p>
Install custom error handler.<p>
Allow the library's user to specify his own error handler function. A valid error handler is a C function with the following prototype:<p>
<pre>
     void MyErrorHandler(CPLErr eErrClass, int err_no, const char *msg)
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Pass NULL to come back to the default behavior. The default behaviour (CPLDefaultErrorHandler()) is to write the message to stderr.<p>
The msg will be a partially formatted error message not containing the "ERROR %d:" portion emitted by the default handler. Message formatting is handled by <a class="el" href="cpl__error_8h.html#ad2b98dd58e4de706a245faddac90403">CPLError()</a> before calling the handler. If the error handler function is passed a CE_Fatal class error and returns, then <a class="el" href="cpl__error_8h.html#ad2b98dd58e4de706a245faddac90403">CPLError()</a> will call abort(). Applications wanting to interrupt this fatal behaviour will have to use longjmp(), or a C++ exception to indirectly exit the function.<p>
Another standard error handler is CPLQuietErrorHandler() which doesn't make any attempt to report the passed error or warning messages but will process debug messages via CPLDefaultErrorHandler.<p>
Note that error handlers set with <a class="el" href="cpl__error_8h.html#74d0e649d58180e621540bf73b58e4a2">CPLSetErrorHandler()</a> apply to all threads in an application, while error handlers set with CPLPushErrorHandler are thread-local. However, any error handlers pushed with CPLPushErrorHandler (and not removed with CPLPopErrorHandler) take precidence over the global error handlers set with <a class="el" href="cpl__error_8h.html#74d0e649d58180e621540bf73b58e4a2">CPLSetErrorHandler()</a>. Generally speaking <a class="el" href="cpl__error_8h.html#74d0e649d58180e621540bf73b58e4a2">CPLSetErrorHandler()</a> would be used to set a desired global error handler, while <a class="el" href="cpl__error_8h.html#d13c9c8f2037ddfd566c2a197f7b2537">CPLPushErrorHandler()</a> would be used to install a temporary local error handler, such as CPLQuietErrorHandler() to suppress error reporting in a limited segment of code.<p>
<dl compact><dt><b>Parameters:</b></dt><dd>
  <table border="0" cellspacing="2" cellpadding="0">
    <tr><td valign="top"></td><td valign="top"><em>pfnErrorHandlerNew</em>&nbsp;</td><td>new error handler function. </td></tr>
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<dl class="return" compact><dt><b>Returns:</b></dt><dd>returns the previously installed error handler. </dd></dl>

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