digitalmars.D.bugs - named union : needs 'this' to access member error
- David L. Davis <SpottedTiger yahoo.com> Jun 17 2005
- Derek Parnell <derek psych.ward> Jun 17 2005
- Tom S <h3r3tic remove.mat.uni.torun.pl> Jun 17 2005
- David L. Davis <SpottedTiger yahoo.com> Jun 17 2005
- Tom S <h3r3tic remove.mat.uni.torun.pl> Jun 17 2005
- David L. Davis <SpottedTiger yahoo.com> Jun 17 2005
- Tom S <h3r3tic remove.mat.uni.torun.pl> Jun 18 2005
# // needthis.d
# // WinXP SP2, D v0.127
# // BUG: "need 'this' to access member AsciiChar"
# // Seems like a named union error, because if it's
# // unnamed it works just fine, but it's a MS struct
# // so I need it the way it is.
# private import std.c.windows.windows;
#
# extern( Windows )
# {
# struct CHAR_INFO
# {
# union Char //<-- if Char is commented out...ok
# {
# WCHAR UnicodeChar;
# CHAR AsciiChar;
# }
#
# WORD Attributes;
# };
# }
#
# int main()
# {
# CHAR_INFO chiFill;
# chiFill.Char.AsciiChar = cast(char)'\x20'; //<--need 'this' to access
# // member AsciiChar
# //chiFill.AsciiChar = cast(char)' '; //<-- works with Char commented out
# return 0;
# }
Output:
----------
C:\dmd>dmd needthis.d
needthis.d(26): need 'this' to access member AsciiChar
C:\dmd>
David L.
-------------------------------------------------------------------
"Dare to reach for the Stars...Dare to Dream, Build, and Achieve!"
-------------------------------------------------------------------
MKoD: http://spottedtiger.tripod.com/D_Language/D_Main_XP.html
Jun 17 2005
On Sat, 18 Jun 2005 02:24:55 +0000 (UTC), David L. Davis wrote:# // needthis.d # // WinXP SP2, D v0.127 # // BUG: "need 'this' to access member AsciiChar" # // Seems like a named union error, because if it's # // unnamed it works just fine, but it's a MS struct # // so I need it the way it is. # private import std.c.windows.windows; # # extern( Windows ) # { # struct CHAR_INFO # { # union Char //<-- if Char is commented out...ok # { # WCHAR UnicodeChar; # CHAR AsciiChar; # } # # WORD Attributes; # }; # } # # int main() # { # CHAR_INFO chiFill; # chiFill.Char.AsciiChar = cast(char)'\x20'; //<--need 'this' to access # // member AsciiChar # //chiFill.AsciiChar = cast(char)' '; //<-- works with Char commented out # return 0; # } Output: ---------- C:\dmd>dmd needthis.d needthis.d(26): need 'this' to access member AsciiChar C:\dmd>
If you name a union, then you must create an instance of it before you can reference its members. If you don't name a union, then the union becomes its own instance. struct CHAR_INFO { union { WCHAR UnicodeChar; CHAR AsciiChar; } } In this case, the anonymous union is also an instance of itself so you can reference its members directly. CHAR_INFO chiFill; chiFill.UnicodeChar = '\x20'; However ... struct CHAR_INFO { union Char { WCHAR UnicodeChar; CHAR AsciiChar; } Char aChar; } In this case, the union is named so you have to create an instance of it first, then reference member through that instance. CHAR_INFO chiFill; chiFill.aChar.UnicodeChar = '\x20'; If you use the union name itself in the reference, then you need to only reference 'static' members, and I'm not sure what that would be. -- Derek Melbourne, Australia 18/06/2005 12:46:21 PM
Jun 17 2005
Tom S <h3r3tic remove.mat.uni.torun.pl> Damn, Derek was faster ;) -- Tomasz Stachowiak /+ a.k.a. h3r3tic +/
Jun 17 2005
In article <trarz7rthih8.140fc8415dmrw$.dlg 40tude.net>, Derek Parnell says...Not a bug. If you name a union, then you must create an instance of it before you can reference its members. If you don't name a union, then the union becomes its own instance. struct CHAR_INFO { union { WCHAR UnicodeChar; CHAR AsciiChar; } } In this case, the anonymous union is also an instance of itself so you can reference its members directly. CHAR_INFO chiFill; chiFill.UnicodeChar = '\x20'; However ... struct CHAR_INFO { union Char { WCHAR UnicodeChar; CHAR AsciiChar; } Char aChar; } In this case, the union is named so you have to create an instance of it first, then reference member through that instance. CHAR_INFO chiFill; chiFill.aChar.UnicodeChar = '\x20'; If you use the union name itself in the reference, then you need to only reference 'static' members, and I'm not sure what that would be. -- Derek Melbourne, Australia 18/06/2005 12:46:21 PM
Thanks Derek...funny thing tho, this example is a part of some D code that compiled fine with D v0.97 in July 2004 ( somehow I missed retesting this code some 30 version of D ago :P ). Thanks again. David L. ------------------------------------------------------------------- "Dare to reach for the Stars...Dare to Dream, Build, and Achieve!" ------------------------------------------------------------------- MKoD: http://spottedtiger.tripod.com/D_Language/D_Main_XP.html
Jun 17 2005
I believe it's intended to work this way... Make the union's name e.g.
UChar and then declare it inside the struct, like:
# struct CHAR_INFO
# {
# union UChar
# {
# WCHAR UnicodeChar;
# CHAR AsciiChar;
# }
#
# UChar Char;
# WORD Attributes;
# }
David L. Davis wrote:
# // needthis.d
# // WinXP SP2, D v0.127
# // BUG: "need 'this' to access member AsciiChar"
# // Seems like a named union error, because if it's
# // unnamed it works just fine, but it's a MS struct
# // so I need it the way it is.
# private import std.c.windows.windows;
#
# extern( Windows )
# {
# struct CHAR_INFO
# {
# union Char //<-- if Char is commented out...ok
# {
# WCHAR UnicodeChar;
# CHAR AsciiChar;
# }
#
# WORD Attributes;
# };
# }
#
# int main()
# {
# CHAR_INFO chiFill;
# chiFill.Char.AsciiChar = cast(char)'\x20'; //<--need 'this' to access
# // member AsciiChar
# //chiFill.AsciiChar = cast(char)' '; //<-- works with Char commented out
# return 0;
# }
Output:
----------
C:\dmd>dmd needthis.d
needthis.d(26): need 'this' to access member AsciiChar
--
Tomasz Stachowiak /+ a.k.a. h3r3tic +/
Jun 17 2005
In article <d902fe$2gfd$1 digitaldaemon.com>, Tom S says...I believe it's intended to work this way... Make the union's name e.g. UChar and then declare it inside the struct, like: # struct CHAR_INFO # { # union UChar # { # WCHAR UnicodeChar; # CHAR AsciiChar; # } # # UChar Char; # WORD Attributes; # } David L. Davis wrote:# // needthis.d # // WinXP SP2, D v0.127 # // BUG: "need 'this' to access member AsciiChar" # // Seems like a named union error, because if it's # // unnamed it works just fine, but it's a MS struct # // so I need it the way it is. # private import std.c.windows.windows; # # extern( Windows ) # { # struct CHAR_INFO # { # union Char //<-- if Char is commented out...ok # { # WCHAR UnicodeChar; # CHAR AsciiChar; # } # # WORD Attributes; # }; # } # # int main() # { # CHAR_INFO chiFill; # chiFill.Char.AsciiChar = cast(char)'\x20'; //<--need 'this' to access # // member AsciiChar # //chiFill.AsciiChar = cast(char)' '; //<-- works with Char commented out # return 0; # } Output: ---------- C:\dmd>dmd needthis.d needthis.d(26): need 'this' to access member AsciiChar
-- Tomasz Stachowiak /+ a.k.a. h3r3tic +/
Thanks Tomasz! BTW, your handle / alias "h3r3tic" reminds me of someone that had a similar name, who I remember made good levels / maps for "Heretic 2" back in the day. David L. ------------------------------------------------------------------- "Dare to reach for the Stars...Dare to Dream, Build, and Achieve!" ------------------------------------------------------------------- MKoD: http://spottedtiger.tripod.com/D_Language/D_Main_XP.html
Jun 17 2005
David L. Davis wrote:BTW, your handle / alias "h3r3tic" reminds me of someone that had a similar name, who I remember made good levels / maps for "Heretic 2" back in the day.
Not me, sorry ;) I enjoyed playing Heretic2 but I never made a map for it -- Tomasz Stachowiak /+ a.k.a. h3r3tic +/
Jun 18 2005