RE: [UV] Pass by value [was:Need/Want/Would like to know]
Maybe passing a matrix in parentheses DOES pass by value - it passes the value of the matrix reference! Which still contains pointers to the matrix elements ... :-) With respect to the docu, I suspect it's meaningless when talking about matrices because it's not talking about what you think it is. For the same reason that C actively discourages passing structs by value (it's a HORRENDOUS performance hit on anything beyond the trivial), I suspect UV doesn't pass matrix CONTENTS by value for the same reason. Cheers, Wol -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Stuart Boydell Sent: 17 February 2004 23:10 To: U2 Users Discussion List Subject: [UV] Pass by value [was:Need/Want/Would like to know] I know that UDT passes by reference Interesting. The UV documentation for the CALL statement says: All scalar and matrix variables are passed to subroutines by reference. If you want to pass variables by value, enclose them in parentheses. Enclosing a matrix in parentheses apparently does not actually work. (UV10.0.7 aix) Vlisting the difference between a scalar and a vector (1D matrix) variable surrounded by parentheses shows in the first example, using a scalar variable, passes by value using a new internal variable _T. In the second example, surrounding a vector in parentheses does nothing and the vector is passed by reference, the same as if there were no parentheses. --- 1 5: CALL P2((A), MAT X) 5 00022 : 0F8 move A = _T 5 00028 : 01E call P2 _T X --- 2 5: CALL P2((X(100)), MAT X) 5 00018 : 01E call P2 X(100(1(X Seems like a bug in the documentation. Stuart ** This email message and any files transmitted with it are confidential and intended solely for the use of addressed recipient(s). If you have received this email in error please notify the Spotless IS Support Centre (61 3 9269 7555) immediately who will advise further action. This footnote also confirms that this email message has been scanned for the presence of computer viruses. ** -- u2-users mailing list [EMAIL PROTECTED] http://www.oliver.com/mailman/listinfo/u2-users *** This transmission is intended for the named recipient only. It may contain private and confidential information. If this has come to you in error you must not act on anything disclosed in it, nor must you copy it, modify it, disseminate it in any way, or show it to anyone. Please e-mail the sender to inform us of the transmission error or telephone ECA International immediately and delete the e-mail from your information system. Telephone numbers for ECA International offices are: Sydney +61 (0)2 9911 7799, Hong Kong + 852 2121 2388, London +44 (0)20 7351 5000 and New York +1 212 582 2333. *** -- u2-users mailing list [EMAIL PROTECTED] http://www.oliver.com/mailman/listinfo/u2-users
RE: [UV] Pass by value [was:Need/Want/Would like to know]
Maybe passing a matrix in parentheses DOES pass by value - it passes the value of the matrix reference! Which still contains pointers to the matrix elements ... :-) With respect to the docu, I suspect it's meaningless when talking about matrices because it's not talking about what you think it is. For the same reason that C actively discourages passing structs by value (it's a HORRENDOUS performance hit on anything beyond the trivial), I suspect UV doesn't pass matrix CONTENTS by value for the same reason. Thanks but I'm not convinced. I still think this is buggy behaviour or bad documentation. My reasons for not being convinced are: A scalar and a matrix variable may refer to the same types of things (value, pointer, dyn array etc). Scalar variables with datum over eight bytes are pointers - same as a matrix variable. So in this case there is virtually no difference between a scalar variable and matrix variable. The documentation suggests that the effect of pass-by-value-parentheses will be the same on either scalar or matrix variable. The documentation says : When data is passed by value, the contents of the variable in the main program do not change as a result of manipulations to the data in the subroutine. This rule breaks when passing a matrix variable by value. The compiler will specifically fail on a call xxx((mat array)) type syntax. This specifically excises passing whole dimensioned arrays by value (your HORRENDOUS struct scenario). The compiler does not fail on a call xxx((array(9))) type syntax suggesting to the developer that certain behaviour will be exhibited. This expected behaviour is not manifested. The compiler treats scalar or matrix variables differently. So, to summarise, I feel my thesis is sound and the U2 developers should either amend the documentation of fix the compiler so that passing a matrix variable by value works. Regards, Stuart Note: in researching this I discovered there are 2 types of dimensioned arrays Prime and Pick style. I tested this for both styles of array with negative results. ** This email message and any files transmitted with it are confidential and intended solely for the use of addressed recipient(s). If you have received this email in error please notify the Spotless IS Support Centre (61 3 9269 7555) immediately who will advise further action. This footnote also confirms that this email message has been scanned for the presence of computer viruses. ** -- u2-users mailing list [EMAIL PROTECTED] http://www.oliver.com/mailman/listinfo/u2-users
RE: [UV] Pass by value [was:Need/Want/Would like to know]
Hello, Stuart. I say this is a compiler flaw rather than a documentation flaw. While it may prove challenging to dig through the parse-tree to figure out when to make use of the implicit temporary, it should be done for matrix components as it is for scalars. The compiler can do it far more reliably for us than we can manually. Best regards, Gyle -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Stuart Boydell Sent: Wednesday, February 18, 2004 5:27 PM To: U2 Users Discussion List Subject: RE: [UV] Pass by value [was:Need/Want/Would like to know] [snip] So, to summarise, I feel my thesis is sound and the U2 developers should either amend the documentation of fix the compiler so that passing a matrix variable by value works. [snip] -- u2-users mailing list [EMAIL PROTECTED] http://www.oliver.com/mailman/listinfo/u2-users
RE: [UV] Pass by value [was:Need/Want/Would like to know]
EQUATE CONST LIT ':' CALL xxx(CONST zzz(n)) Good call! ** This email message and any files transmitted with it are confidential and intended solely for the use of addressed recipient(s). If you have received this email in error please notify the Spotless IS Support Centre (61 3 9269 7555) immediately who will advise further action. This footnote also confirms that this email message has been scanned for the presence of computer viruses. ** -- u2-users mailing list [EMAIL PROTECTED] http://www.oliver.com/mailman/listinfo/u2-users
RE: [UV] Pass by value [was:Need/Want/Would like to know]
I say this is a compiler flaw rather than a documentation flaw. While it may prove challenging to dig through the parse-tree to figure out when to make use of the implicit temporary, it should be done for matrix components as it is for scalars. The compiler can do it far more reliably for us than we can manually. Best regards, Gyle Sounds good. Cheers S ** This email message and any files transmitted with it are confidential and intended solely for the use of addressed recipient(s). If you have received this email in error please notify the Spotless IS Support Centre (61 3 9269 7555) immediately who will advise further action. This footnote also confirms that this email message has been scanned for the presence of computer viruses. ** -- u2-users mailing list [EMAIL PROTECTED] http://www.oliver.com/mailman/listinfo/u2-users
RE: [UV] Pass by value [was:Need/Want/Would like to know]
Hello, Stuart. Hmmm. The technique shown deals with string, real and whole number variables. What about files, subroutines, sockets, etc? And performing string concatenation would coerce numerics into strings, which may slow things further down stream. Best regards, Gyle -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Stuart Boydell Sent: Wednesday, February 18, 2004 6:20 PM To: U2 Users Discussion List Subject: RE: [UV] Pass by value [was:Need/Want/Would like to know] EQUATE CONST LIT ':' CALL xxx(CONST zzz(n)) Good call! [snip] -- u2-users mailing list [EMAIL PROTECTED] http://www.oliver.com/mailman/listinfo/u2-users
