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OpenBoard/thirdparty/quazip/doc/usage.dox

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/** \page usage Usage
*
* This page provides general information on QuaZIP usage. See classes
* QuaZip and QuaZipFile for the detailed documentation on what can
* QuaZIP do and what can not. Also, reading comments in the zip.h and
* unzip.h files (taken from the original ZIP/UNZIP package) is always a
* good idea too. After all, QuaZIP is just a wrapper with a few
* convenience extensions and reimplementations.
*
* QuaZip is a class representing ZIP archive, QuaZipFile represents a
* file inside archive and subclasses QIODevice as well.
*
* \section terminology Terminology
*
* "QuaZIP" means whole this library, while "QuaZip" (not case
* difference) is just one class in it.
*
* "ZIP/UNZIP API" means the original API of the Gilles Vollant's
* ZIP/UNZIP package. I did not alter it in any way to make it easier to
* port to the future ZIP/UNZIP versions.
*
* "ZIP", "ZIP archive" or "ZIP file" means any ZIP archive. Typically
* this is a plain file with ".zip" (or ".ZIP") file name suffix.
*
* "A file inside archive", "a file inside ZIP" or something like that
* means file either being read or written from/to some ZIP archive.
*
* \section error-handling Error handling
*
* Almost any call to ZIP/UNZIP API return some error code. Most of the
* original API's error checking could be done in this wrapper as well,
* but it would cause unnecessary code bloating without any benefit. So,
* QuaZIP only checks for situations that ZIP/UNZIP API can not check
* for. For example, ZIP/UNZIP API has no "ZIP open mode" concept
* because read and write modes are completely separated. On the other
* hand, to avoid creating classes like "QuaZipReader", "QuaZipWriter"
* or something like that, QuaZIP introduces "ZIP open mode" concept
* instead, thus making it possible to use one class (QuaZip) for both
* reading and writing. But this leads to additional open mode checks
* which are not done in ZIP/UNZIP package.
*
* Therefore, error checking is two-level (QuaZIP's level and ZIP/UNZIP
* API level), which sometimes can be confusing, so here are some
* advices on how the error checking should be properly done:
*
* - Both QuaZip and QuaZipFile have getZipError() function, which return
* error code of the last ZIP/UNZIP API call. Most function calls
* reset error code to UNZ_OK on success and set error code on
* failure. Some functions do not reset error code. Most of them are
* \c const and do not access ZIP archive in any way. Some, on the
* other hand, \em do access ZIP archive, but do not reset or set
* error code. For example, QuaZipFile::pos() function. Such functions
* are explicitly marked in the documentation.
* - Most functions have its own way to report errors, by returning a
* null string, negative value or \c false. If such a function returns
* error value, call getZipError() to get more information about
* error. See "zip.h" and "unzip.h" of the ZIP/UNZIP package for error
* codes.
* - If the function returns error-stating value (like \c false), but
* getZipError() returns UNZ_OK, it means that you did something
* obviously wrong. For example, tried to write in the archive open
* for reading or not open at all. You better just do not do that!
* Most functions also issue a warning using qWarning() function in
* such cases. See documentation for a specific function for details
* on when it should not be called.
*
* I know that this is somewhat messy, but I could not find a better way
* to do all the error handling.
**/