[Issue 9408] invariant should be non-const by default and settable to const

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https://issues.dlang.org/show_bug.cgi?id=9408

Andrej Mitrovic  changed:

   What|Removed |Added

 Status|NEW |RESOLVED
 Resolution|--- |INVALID

--- Comment #5 from Andrej Mitrovic  ---
I'm closing this as invalid unless someone comes up with a DIP with all the
pro's and con's. When looking at it from a safety point of view I'd rather not
have someone accidentally modify a variable in an invariant of all places.

Imagine a debug build where a variable was assigned to and made an app work
fine, and then a -release build was deployed without the assignment and causing
hard to track bugs.

--

[Issue 9408] invariant should be non-const by default and settable to const

[d-bugmail]

https://d.puremagic.com/issues/show_bug.cgi?id=9408


Andrej Mitrovic andrej.mitrov...@gmail.com changed:

   What|Removed |Added

   Keywords||pull
 AssignedTo|andrej.mitrov...@gmail.com  |nob...@puremagic.com


--- Comment #4 from Andrej Mitrovic andrej.mitrov...@gmail.com 2014-02-03 
06:09:05 PST ---
Unassigning myself until there's a consensus.

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[Issue 9408] invariant should be non-const by default and settable to const

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http://d.puremagic.com/issues/show_bug.cgi?id=9408


Walter Bright bugzi...@digitalmars.com changed:

   What|Removed |Added

 CC||bugzi...@digitalmars.com


--- Comment #2 from Walter Bright bugzi...@digitalmars.com 2013-02-03 
11:20:58 PST ---
I think this change is a step backwards.

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[Issue 9408] invariant should be non-const by default and settable to const

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http://d.puremagic.com/issues/show_bug.cgi?id=9408


bearophile_h...@eml.cc changed:

   What|Removed |Added

 CC||bearophile_h...@eml.cc


--- Comment #3 from bearophile_h...@eml.cc 2013-02-03 11:43:10 PST ---
(In reply to comment #2)
 I think this change is a step backwards.

I think in this discussion there are two main sides:

Some people want to write D code right now, so they don't want to fight too
much with problems caused by const. And they like freedom. Often this side is
also associated with the worse is better language design philosophy.

They other camp reads the texts written by the creator of the Eiffel language,
that explain what Contracts are and what they are meant to. For them a
precondition or an invariant should never modify the state of the struct/class.
And the language should enforce this, to avoid bugs. They accept less a bit
less convenience for stronger guarantees and cleaner code.
Mathematics-oriented people are often on this side.

D language has introduced const/invariant, but it's so strong that sometimes
you don't want or your can't use it. So sometimes D programmers don't want to
eat their own dog food.

I generally prefer a more clean style of coding, because from experience I
have seen that the amount of time wasted making a fussy type system happy, is
often paid later in less bugs, that otherwise waste far more of my time.

But in the end I sympathize with both camps, for different reasons. Both are
partially right. In the end a static analysis tool can just enforce all
invariants to be tagged with const, so the end result is not too much
different.

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[Issue 9408] invariant should be non-const by default and settable to const

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http://d.puremagic.com/issues/show_bug.cgi?id=9408



--- Comment #1 from Andrej Mitrovic andrej.mitrov...@gmail.com 2013-01-26 
21:45:00 PST ---
https://github.com/D-Programming-Language/dmd/pull/1560

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