• nascent (7/7) Feb 17 2006 I can't find good documentation on this like with readf. How exactly
• Chris Sauls (14/22) Feb 17 2006 The 'in' attribute is mostly just there for completeness (for now, some ...
• nascent (2/33) Feb 18 2006

nascent <jesse.phillips eagles.ewu.edu> writes:

I can't find good documentation on this like with readf. How exactly 
should the function(in var, out var2, inout var3) tagging be used? The 
ones with out are set to the initializer value, but I would think most 
people like using the values they pass in? So a good explanation of this 
would be nice, and it doesn't have to be D related if it is found 
elsewhere, but could someone point me in the right direction?

--Jesse

Chris Sauls <ibisbasenji gmail.com> writes:

nascent wrote:
 I can't find good documentation on this like with readf. How exactly 
 should the function(in var, out var2, inout var3) tagging be used? The 
 ones with out are set to the initializer value, but I would think most 
 people like using the values they pass in? So a good explanation of this 
 would be nice, and it doesn't have to be D related if it is found 
 elsewhere, but could someone point me in the right direction?
 
 --Jesse

The 'in' attribute is mostly just there for completeness (for now, some
proposals suggest 
changing it to have a new meaning, but I won't get in to that).  It just
represents the 
normal pass-by-value behavior.

The 'out' attribute re-initializes the variable, and then passes it by
reference. 
Basically, its for passing a buffer.

The 'inout' attribute establishes pass-by-reference without any processing of
the 
variable.  So if you want to use the value passed, /and/ want to be able to
edit that 
value in place, use 'inout'.  If you don't care about the value passed in, use
'out'.  If 
you don't want the variable's value changed at all, use 'in'.

Of course this doesn't account for slice semantics, and object variables are
technically 
always references -- which means that the 'in' behavior just prevents you from
changing 
/which object/ the variable references.  You can still modify that object.

-- Chris Nicholson-Sauls

nascent <jesse.phillips eagles.ewu.edu> writes:

Thanks, I'll have to try it some time.

Chris Sauls wrote:
 nascent wrote:
 
 I can't find good documentation on this like with readf. How exactly 
 should the function(in var, out var2, inout var3) tagging be used? The 
 ones with out are set to the initializer value, but I would think most 
 people like using the values they pass in? So a good explanation of 
 this would be nice, and it doesn't have to be D related if it is found 
 elsewhere, but could someone point me in the right direction?

 --Jesse

 
 
 The 'in' attribute is mostly just there for completeness (for now, some 
 proposals suggest changing it to have a new meaning, but I won't get in 
 to that).  It just represents the normal pass-by-value behavior.
 
 The 'out' attribute re-initializes the variable, and then passes it by 
 reference. Basically, its for passing a buffer.
 
 The 'inout' attribute establishes pass-by-reference without any 
 processing of the variable.  So if you want to use the value passed, 
 /and/ want to be able to edit that value in place, use 'inout'.  If you 
 don't care about the value passed in, use 'out'.  If you don't want the 
 variable's value changed at all, use 'in'.
 
 Of course this doesn't account for slice semantics, and object variables 
 are technically always references -- which means that the 'in' behavior 
 just prevents you from changing /which object/ the variable references.  
 You can still modify that object.
 
 -- Chris Nicholson-Sauls