pfe-environ-ext ? Environment related definitions
ENVIRONMENT? ( name-ptr name-len -- 0 | ?? name-flag! ) ?=>? ( | ); | ? |
[FORTH];REQUIRED ( ... str-ptr str-len -- ??? ) ?=>? ( | ); | ? |
[FORTH];REQUIRE ( ... "file-name" -- ... ) ?=>? ( | ); | ? |
[FORTH];NEEDS ( name -- ) ?=>? ( | ); | ? |
[FORTH];
ENVIRONMENT? ( name-ptr name-len -- 0 | ?? name-flag! ) [ANS] => [FORTH]
check the environment for a property, usually a condition like questioning the existance of specified wordset, but it can also return some implementation properties like "WORDLISTS" (the length of the search-order) or "#LOCALS" (the maximum number of locals)
Here it implements the environment queries as a SEARCH-WORDLIST
in a user-visible vocabulary called ENVIRONMENT
: ENVIRONMENT?
['] ENVIRONMENT >WORDLIST SEARCH-WORDLIST
IF EXECUTE TRUE ELSE FALSE THEN ;
REQUIRED ( ... str-ptr str-len -- ??? ) => [FORTH]
the filename argument is loaded via INCLUDED as
an extension package to the current system. The filename
is registered in the current ENVIRONMENT so that it is
only INCLUDED once (!!) if called multiple times via
REQUIRED or REQUIRES
REQUIRE ( ... "file-name" -- ... ) => [FORTH]
parses the next WORD and passes it to REQUIRED
this is the self-parsing version of REQUIRED and
it does parrallel INCLUDE w.r.t. INCLUDED
NEEDS ( name -- ) => [FORTH]
A self-parsing variant of an environment-query check. It is similar to a simulation like
: NEEDS PARSE-WORD 2DUP ENVIRONMENT?
IF DROP ( extra value ) 2DROP ( success - be silent )
ELSE TYPE ." not available " CR THEN ;
however that would only match those worset-envqueries which return a single extra item under the uppermost TRUE flag in the success case. Instead it works more like
: NEEDS PARSE-WORD 2DUP ENVIRONMENT-WORDLIST SEARCH-WORDLIST
IF 2DROP ( success - be silent and just drop the parsed word )
ELSE TYPE ." not available " CR THEN ;
however we add the same extension as in ENVIRONMENT? as that
it can automatically load a wordset module to fullfil a query
that looks like "[wordsetname]-ext". Therefore, the following
two lines are pretty much identical:
LOADM floating NEEDS floating-ext
the difference between the two: if somebody did provide a forth
level implementation of floating-ext then that implementation might
have registered a hint "floating-ext" in the environment-wordlist.
This extra-hint will inhibit loading of the binary module even if
it exists and not been loaded so far. The LOADM however will
not check the ENVIRONMENT-WORDLIST and only check its loadlist
of binary wordset modules in the system.
It is therefore recommended to use NEEDS instead of LOADM
unless you know you want the binary module, quickly and uncondtionally.