Core API

< 2.1.6. Import and install of extensions  Table Of Content 2.1.8. ext_emconf.php >

2.1.7. ext_tables.php and ext_localconf.php

These two files are the most important for the execution of extensions to TYPO3. They contain configuration used within the system on almost every request. Therefore they should be optimized for speed.

  1. ext_localconf.php is always included in global scope of the script, either frontend or backend.
    You can put functions and classes into the script, but you should consider doing that in other ways because such classes and functions would always be available - and it would be better if they were included only when needed.
    So stick to change values in TYPO3_CONF_VARS only!

  2. ext_tables.php is not always included in global scope on the other hand (in the frontend)
    Don't put functions and classes - or include other files which does - into this script!

  3. Use the API of the class extMgm for various manipulative tasks such as adding tables, merging information into arrays etc.

  4. Before the inclusion of any of the two files, the variables $_EXTKEY is set to the extention-key name of the module and $_EXTCONF is set to the configuration from $TYPO3_CONF_VARS["EXT"]["extConf"][extension key]

  5. $TYPO3_LOADED_EXT[extension key] contains information about whether the module is loaded as local, global or system type, including the proper paths you might use, absolute and relative.

  6. The inclusion can happen in two ways:

    1. 1) Either the files are included individually on each request (many file includes) ($TYPO3_CONF_VARS["EXT"]["extCache"]=0;)

    2. 2) or (better) the files are automatically imploded into one single temporary file (cached) in typo3conf/ directory (only one file include) ($TYPO3_CONF_VARS["EXT"]["extCache"]=1;  [or 2]). This is default (value "1")

In effect this means:

  1. Your ext_tables.php / ext_localconf.php file must be designed so that it can safely be read and subsequently imploded into one single file with all the other configuration scripts!

  2. You must NEVER use a "return" statement in the files global scope - that would make the cached script concept break.

  3. You should NOT rely on the PHP constant __FILE__ for detection of include path of the script - the configuration might be executed from a cached script and therefore such information should be derived from the $TYPO3_LOADED_EXT[extension key] array. Eg. $TYPO3_LOADED_EXT[$_EXTKEY]["siteRelPath"]

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