The GNAT library contains a number of general and special purpose packages. It represents functionality that the GNAT developers have found useful, andwhich is made available to GNAT users. The packages described here are fullysupported, and upwards compatibility will be maintained in future releases,so you can use these facilities with the confidence that the same functionalitywill be available in future releases.
The chapter here simply gives a brief summary of the facilities available. The full documentation is found in the spec file for the package. The fullsources of these library packages, including both spec and body, are providedwith all GNAT releases. For example, to find out the full specifications ofthe SPITBOL pattern matching capability, including a full tutorial andextensive examples, look in theg-spipat.ads file in the library.
For each entry here, the package name (as it would appear in awithclause) is given, followed by the name of the corresponding spec file inparentheses. The packages are children in four hierarchies,Ada,Interfaces,System, andGNAT, the latter being aGNAT-specific hierarchy.
Note that an application program should only use packages in one of thesefour hierarchies if the package is defined in the Ada Reference Manual,or is listed in this section of the GNAT Programmers Reference Manual. All other units should be considered internal implementation units andshould not be directlywith'ed by application code. The use ofawith statement that references one of these internal implementationunits makes an application potentially dependent on changes in versionsof GNAT, and will generate a warning message.