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2013-04-18 14:58 UTC+0200 Przemysław Czerpak (druzus/at/poczta.onet.pl)

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* .gitignore
    ! removed executable file permission

  * package/mpkg_src.sh
    ! added executable file permission

  * contrib/hbct/screen2.c
    % use STR API for parameters instead of using local conversions

  * contrib/hbct/token1.c
    % small simplification

  * contrib/hbnetio/netiosrv.c
    + respect timeout parameter also in send operation

  * contrib/make.hb
    ! moved project name normalization and directory verification to
      AddProject() function. It fixes HB_BUILD_ADDONS envvar functionality.

  * doc/xhb-diff.txt
    + added new paragraph: DECLARATION AND INITIALIZATION OF VARIABLES

  * src/rtl/hbcom.c
    * added 3-rd parameter to TIOCEXCL and TIOCNXCL ioctl() codes
      to pacify valgrind warnings

  * include/hbexpra.c
    ! fixed compilation with HB_USE_ENUM_FUNCTIONS macro

  * include/hbapicls.h
  * include/hbcompdf.h
  * include/hbexpra.c
  * src/compiler/harbour.y
  * src/vm/classes.c
    + added support for :__enumIsFirst() iterator message. It's opposite
      to recently added :__enumIsLast()
    + added support for overloading :__enumIsFirst() and :__enumIsLast()
      functionality in custom FOR EACH implementations

  * include/hbcompdf.h
  * include/hbexpra.c
  * src/compiler/harbour.y
    + added support for reverting :__enumIsFirst() and :__enumIsLast()
      messages in descendant FOR EACH loops. It's disabled now by 2 #if 0
      but I think it should be discussed. Should we keep it enable it?
      The answer is not trivial when FOR EACH is used to iterate some
      objects. In general such names are confusing.

  * src/compiler/harbour.yyc
  * src/compiler/harbour.yyh
    * regenerated using bison 2.5

  * tests/foreach.prg
    + added :__enumIsFirst() to test code

  * tests/foreach2.prg
    ! typo in comment
This commit is contained in:
Przemysław Czerpak
2013-04-18 14:58:40 +02:00
parent 6ad5bb4355
commit 877ddb4a06
18 changed files with 890 additions and 664 deletions
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99
doc/xhb-diff.txt
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@@ -521,6 +521,105 @@ references by detached locals and add workarounds for it if necessary.
### DECLARATION AND INITIALIZATION OF VARIABLES ###
=========================================================
Clipper parses variable declaration in a little bit different way then
Harbour and xHarbour. It makes it in two passes. In first pass it collects
names and scope of all declared variables and then in second pass this
information is available during variable initialization. This can be
illustrated by the following example:
/*** tst.prg ***/
proc main()
local cb := {|| qout( n + 5 ), qout( f ) } // (*)
field f in table
local n := 10
eval( cb )
return
In the line which initialize cb code (*) we are using local variable n
and field f. Both are declared below the line in which codeblock is
initialized anyhow Clipper does not recognize it as undeclared variables
and use their later declarations. If you compile above code using Clipper
with -n -w -es2 switches, i.e.
cl tst -n -w -es2
then it's compiled without any compile time warnings or errors. Then
during execution it shows 15 for the first QOUT() function call and
generate runtime error
Error BASE/1002 Alias does not exist: TABLE
for the second QOUT() call. It means that it correctly recognized scope
of both variables and also bound alias TABLE with field F though it was
declared two lines below codeblock initialization.
In fact Clipper probably does not make two passes but parsing declarations
which have to be at the beginning of function or module it stores names of
variables which should be initialized with the initialization expressions.
Then when all declarations are processed for each line with declared and
initialized variables it generates code which pushes on VM stack results
of initialization expressions and then code which pops it initializing
variables. As result in Clipper this code cannot work:
local x := 10, y := x + 2
because Clipper generate PCODE like:
push 10
push x
push 2
add
pop y
pop x
but this code:
local x := 10
local y := x + 2
works correctly because declarations were in separated lines and in such
case Clipper generates PCODE like:
push 10
pop x
push x
push 2
add
pop y
In Harbour and xHarbour all variables are declared in the moment when they
are processed. It means that during compilation of above example using
harbour tst -n -w -es2
both compilers generate compile time warnings:
tst.prg(2) Warning W0001 Ambiguous reference 'N'
tst.prg(2) Warning W0001 Ambiguous reference 'F'
but it also means that in Harbour and xHarbour it's possible to write code
like:
proc main()
local x := 10, y := x + 2
? x, y
return
and unlike Clipper both compilers generates correct PCODE which shows
10 12
Maybe in the future we add support for Clipper compatible local variable
initialization covered by -kc Harbor compiler switch.
xBase++ uses mixed behavior. Just like Clipper it stores variables with
initialization expressions but then it generates slightly different code
initializing variables one by one without line groping like in Clipper.
Please also note that in Clipper PRIVATE and PUBLIC declarations are
executable statements so they are not used used as declarations by
Clipper compiler even if -a compiler switch is used. So when we talk
about initialization then it means that we are talking about LOCAL
variables. STATIC variables are initialized in different way at
application startup so cannot use local variables though due to but
in Clipper in some cases compiler can accept local variables and then
it may cause VM crash or runtime error, i.e. this code:
proc main()
local n
static s := {|| n }
eval( s )
return
is cleanly compiled by Clipper and xBase++ but it causes RTE in
Clipper and FATAL ERROR LOG in xBase++.
Harbour and xHarbour correctly report compile time error for it.
### FUNCTIONS WITH VARIABLE NUMBER OF PARAMETERS ###
==========================================================
Both compilers supports them though xHarbour is limited to all parameters