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digitalmars.D - Mini proposal: rename float.min to float.min_normal

reply Don <nospam nospam.com> writes:
This is another small imperfection we should get rid of.
The floating point types have a property called ".min", but unlike the 
integer ".min", it's not the minimum!
This naming stupidity is inherited from C++. The minimum float is 
-float.max. Instead, float.min is the minimum representable positive 
normalized number.
(BTW there are also representable "subnormal" numbers between 0 and 
float.min. So the name 'min' is _completely_ inappropriate, it's not 
even the minimum absolute value).

This misnaming is bad because (a) it causes confusion; and (b) it 
interfere with generic code, requiring special cases.
We should rename this while we have the chance. I don't think we should 
depart too far from the C/C++ name, but anything other than ".min" will 
work. I propose:

real.min ----> real.min_normal

Comments:
(1) Embedded underscores are probably not ideal, but they are already in 
use in the floating point properties mant_dig, and the rarely used 
max_10_exp, max_exp, min_10_exp, min_exp. They're also used in 
foreach_reverse, and in the built-in version identifiers, such as X86_64 
and D_InlineAsm_X86. So there seems no reason to avoid them here. But if 
you have a much better idea for a name, speak now!
(2) There's no need for float.max_normal. float.max truly is the maximum 
representable number (excluding infinity).
Although float.min sounds like some kind of inverse of float.max, it is 
not. (The relationship is: X.max * X.min = 4.0 for binary types, 10.0 
for decimal types).
Changing float.min -> float.min_normal will remove that illusion.

If there is no objection to this, I will create a patch. It's very simple.
Oct 23 2009
next sibling parent #ponce <aliloko gmail.com> writes:
I agree, when i had to type float.min i was confused it it was the smallest
subnormal or smallest normal float
Oct 23 2009
prev sibling next sibling parent "Lars T. Kyllingstad" <public kyllingen.NOSPAMnet> writes:
Don wrote:

 This is another small imperfection we should get rid of.
 The floating point types have a property called ".min", but unlike the 
 integer ".min", it's not the minimum!
 This naming stupidity is inherited from C++. The minimum float is 
 -float.max. Instead, float.min is the minimum representable positive 
 normalized number.
 (BTW there are also representable "subnormal" numbers between 0 and 
 float.min. So the name 'min' is _completely_ inappropriate, it's not 
 even the minimum absolute value).
 
 This misnaming is bad because (a) it causes confusion; and (b) it 
 interfere with generic code, requiring special cases.
 We should rename this while we have the chance. I don't think we should 
 depart too far from the C/C++ name, but anything other than ".min" will 
 work. I propose:
 
 real.min ----> real.min_normal
 
 Comments:
 (1) Embedded underscores are probably not ideal, but they are already in 
 use in the floating point properties mant_dig, and the rarely used 
 max_10_exp, max_exp, min_10_exp, min_exp. They're also used in 
 foreach_reverse, and in the built-in version identifiers, such as X86_64 
 and D_InlineAsm_X86. So there seems no reason to avoid them here. But if 
 you have a much better idea for a name, speak now!



After I read your floating-point article on the DMD web site that name 
has been bothering me too. I vote for changing it.

I wouldn't worry about the underscore, as there is already precedence 
for using them in keywords and built-in properties. If people don't like 
that, we should also change the others.

Would it make sense to redefine real.min to mean -real.max? It would at 
least be consistent with the meaning of int.min, and perhaps it would 
find use in generic code.

-Lars
Oct 23 2009
prev sibling next sibling parent Ali Cehreli <acehreli yahoo.com> writes:
Don Wrote:


 The floating point types have a property called ".min", but unlike the 
 integer ".min", it's not the minimum!


That bothered me too when I was writing about it before; I felt embarrassed
when explaining that it was not actually the minimum. :)

Ali
Oct 23 2009
prev sibling next sibling parent reply bearophile <bearophileHUGS lycos.com> writes:
Don:


 such as X86_64 and D_InlineAsm_X86<


I don't like the identifier that denotes D2 code ("D_Version2").



 If there is no objection to this, I will create a patch. It's very simple.


I usually like all your proposals about floating point numbers :-)

Bye,
bearophile
Oct 23 2009
parent reply Jeremie Pelletier <jeremiep gmail.com> writes:
bearophile wrote:

 Don:
 

 such as X86_64 and D_InlineAsm_X86<


 
 I don't like the identifier that denotes D2 code ("D_Version2").


I never use it either, this identifier is rather pointless. Both 
compilers will still parse both conditions and errors on the branch for 
the other version.


 If there is no objection to this, I will create a patch. It's very simple.


 
 I usually like all your proposals about floating point numbers :-)


I agree, its a good change! I would also change float.min to be an alias 
of -float.max.

Jeremie
Oct 24 2009
next sibling parent bearophile <bearophileHUGS lycos.com> writes:
Jeremie Pelletier:


 I never use it either, this identifier is rather pointless. Both 
 compilers will still parse both conditions and errors on the branch for 
 the other version.


Sorry, as usual I want not precise enough, I meant I don't like the name of
that identifier, but I use that functionality, I use version(D_Version2) when I
want to write code that works with both Phobos1 and Phobos2 (so for example I
import to!(int, string) from Phobos2 and toInt from Phobos1).

Bye,
bearophile
Oct 24 2009
prev sibling parent Don <nospam nospam.com> writes:
Jeremie Pelletier wrote:

 I agree, its a good change! I would also change float.min to be an alias 
 of -float.max.


Unfortunately, we can't do that yet, it would silently change the 
meaning of existing code. Hopefully it can be done eventually.
Oct 24 2009
prev sibling next sibling parent Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:
Don wrote:

 This is another small imperfection we should get rid of.
 The floating point types have a property called ".min", but unlike the 
 integer ".min", it's not the minimum!


I've always hated that with a passion. Yes Don, great initiative. Let's 
change that crap once and for all. I'd consider using minNormal, but you 
make a good point that _ is already present.

++vote for patching. There are a couple of places in Phobos that need 
changing, I can operate them.


Andrei
Oct 23 2009
prev sibling parent reply Don <nospam nospam.com> writes:
Don wrote:

 This is another small imperfection we should get rid of.
 The floating point types have a property called ".min", but unlike the 
 integer ".min", it's not the minimum!



 This misnaming is bad because (a) it causes confusion; and (b) it 
 interfere with generic code, requiring special cases.
 We should rename this while we have the chance. I don't think we should 
 depart too far from the C/C++ name, but anything other than ".min" will 
 work. I propose:
 
 real.min ----> real.min_normal
 If there is no objection to this, I will create a patch. It's very simple.


Patch is in bugzilla 3446. It took about 2 minutes to do.
Oct 28 2009
parent Jason House <jason.james.house gmail.com> writes:
Don Wrote:


 Don wrote:

 This is another small imperfection we should get rid of.
 The floating point types have a property called ".min", but unlike the 
 integer ".min", it's not the minimum!


 

 This misnaming is bad because (a) it causes confusion; and (b) it 
 interfere with generic code, requiring special cases.
 We should rename this while we have the chance. I don't think we should 
 depart too far from the C/C++ name, but anything other than ".min" will 
 work. I propose:
 
 real.min ----> real.min_normal
 If there is no objection to this, I will create a patch. It's very simple.


 
 Patch is in bugzilla 3446. It took about 2 minutes to do.


You're missing documentation updates.
Oct 28 2009