File for explaining code quirks/features/caveats
- added NOCWD_ASSUMPTIONS and PREFIXES_IN_USE section.
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DEVEL/code_features.txt
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DEVEL/code_features.txt
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$NHDT-Date: 1426969026 2015/03/21 20:17:06 $ $NHDT-Branch: master $:$NHDT-Revision: 1.137 $
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code_features.txt
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Developer-useful info about code features, assumptions, purpose,
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rationale, etc.
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==============================================
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PREFIXES_IN_USE and NOCWD_ASSUMPTIONS
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Those provide a storage mechanism for holding the paths to various different
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types of files. Those paths are stored in the fqn_prefix[] array. They are a
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mechanism for enabling separation of the different files that NetHack needs.
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The prefixes are added to the beginning of file names by various routines in
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files.c immediately prior to opening one of the types of files that the game
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uses.
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They aren't about config file options (although config file options would be
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one way to set non-default values for some of the paths in the fqn_prefix[]
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array). Obviously the very first path needed (now sysconfdir, previously
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configdir) isn't viable for setting via config file options, but the game
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still needs to hunt it down "someplace." When the "someplace" is figured
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out, that place (path) would be stored in fqn_prefix[SYSCONPREFIX]. How it
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gets stored in fqn_prefix[SYSCONPREFIX] is up to us as developers.
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Any of the fqn_prefix[] entries can be set somehow. It could be done in port
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startup code; in options processing; in config file processing; by
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translating a system environment variable such as USERPROFILE; whatever
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you/we want. The point is that NOCWD_ASSUMPTIONS and PREFIXES_IN_USE are
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there to ensure that there is a place to store that path information. The
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code to *utilize* the information is already in files.c (see fqname()).
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There is a fqn_prefix[] entry for holding the path to each of the following:
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PREFIX NAME
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0 HACKPREFIX hackdir
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1 LEVELPREFIX leveldir location to create level files
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2 SAVEPREFIX savedir location to create/read saved games
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3 BONESPREFIX bonesir location to create/read bones
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4 DATAPREFIX datadir location to read data.base etc.
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5 SCOREPREFIX scoredir location to read/write scorefile
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6 LOCKPREFIX lockdir location to create/read lock files
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7 SYSCONFPREFIX sysconfdir location to read SYSCF_FILE
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8 CONFIGPREFIX configdir location to read user configuration file
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9 TROUBLEPREFIX troubledir location to place panic files etc.
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To recap, they are about enabling "different paths for different things", and
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separation of:
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- read-only stuff from read-write stuff.
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- sysadmin stuff from user-writeable stuff.
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etc.
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=================== NEXT FEATURE ==========================
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