Inside GDALAllRegister之四： 跳过driver

这个函数很短小:

/**
 * rief This method unload undesirable drivers.
 *
 * All drivers specified in the space delimited list in the GDAL_SKIP 
 * environmentvariable) will be deregistered and destroyed.  This method 
 * should normally be called after registration of standard drivers to allow 
 * the user a way of unloading undesired drivers.  The GDALAllRegister()
 * function already invokes AutoSkipDrivers() at the end, so if that functions
 * is called, it should not be necessary to call this method from application
 * code. 
 */

void GDALDriverManager::AutoSkipDrivers()

{
    if( CPLGetConfigOption( "GDAL_SKIP", NULL ) == NULL )
        return;

    char **papszList = CSLTokenizeString( CPLGetConfigOption("GDAL_SKIP","") );

    for( int i = 0; i < CSLCount(papszList); i++ )
    {
        GDALDriver *poDriver = GetDriverByName( papszList[i] );

        if( poDriver == NULL )
            CPLError( CE_Warning, CPLE_AppDefined, 
                      "Unable to find driver %s to unload from GDAL_SKIP environment variable.", 
                      papszList[i] );
        else
        {
            CPLDebug( "GDAL", "AutoSkipDriver(%s)", papszList[i] );
            DeregisterDriver( poDriver );
            delete poDriver;
        }
    }

    CSLDestroy( papszList );
}

如果在环境变量GDAL_SKIP中指定某些driver，可以在运行时将该driver从GDALDriverManger中注销掉。这提供了一个基于配置的解决方案，比起前面通过编译时添加宏多了一个选择。考虑的还是比较周到的。