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not really pure
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@WalterBright
WalterBright committed Jun 26, 2011
1 parent d6c471b commit 4f28db6
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Showing 5 changed files with 294 additions and 294 deletions.
14 changes: 7 additions & 7 deletions std/bigint.d
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Expand Up @@ -366,7 +366,7 @@ public:
}
/// Returns the value of this BigInt as a long,
/// or +- long.max if outside the representable range.
long toLong() pure const
long toLong() const
{
return (sign ? -1 : 1) *
(data.ulongLength() == 1 && (data.peekUlong(0) <= cast(ulong)(long.max))
Expand All @@ -375,7 +375,7 @@ public:
}
/// Returns the value of this BigInt as an int,
/// or +- int.max if outside the representable range.
long toInt() pure const
long toInt() const
{
return (sign ? -1 : 1) *
(data.uintLength() == 1 && (data.peekUint(0) <= cast(uint)(int.max))
Expand All @@ -384,13 +384,13 @@ public:
}
/// Number of significant uints which are used in storing this number.
/// The absolute value of this BigInt is always < 2^^(32*uintLength)
@property size_t uintLength() pure const
@property size_t uintLength() const
{
return data.uintLength();
}
/// Number of significant ulongs which are used in storing this number.
/// The absolute value of this BigInt is always < 2^^(64*ulongLength)
@property size_t ulongLength() pure const
@property size_t ulongLength() const
{
return data.ulongLength();
}
Expand Down Expand Up @@ -440,16 +440,16 @@ private:
if (!data.isZero())
sign = !sign;
}
bool isZero() pure const
bool isZero() const
{
return data.isZero();
}
bool isNegative() pure const
bool isNegative() const
{
return sign;
}
// Generate a runtime error if division by zero occurs
void checkDivByZero() pure const
void checkDivByZero() const
{
assert(!isZero(), "BigInt division by zero");
if (isZero())
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2 changes: 1 addition & 1 deletion std/complex.d
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Expand Up @@ -113,7 +113,7 @@ struct Complex(T) if (isFloatingPoint!T)
T im;


@safe pure nothrow // The following functions depend only on std.math.
@safe nothrow // The following functions depend only on std.math.
{

/** Calculate the absolute value (or modulus) of the number. */
Expand Down

8 comments on commit 4f28db6

@dsimcha
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??? Why isn't the stuff in std.parallelism pure?

@WalterBright
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It's referring to non-immutable members of a non-local variable.

@jmdavis
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Why can't the std.datetime stuff be pure? None of it is accessing non-immutable, non-local variables.

@WalterBright
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@WalterBright WalterBright commented on 4f28db6 Jun 26, 2011 via email

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@dnadlinger
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Walter decided to »tighten purity checks« in dlang/dmd@84b4fd1 …

@jmdavis
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As I understand it, weakly pure functions are supposed to be able to do that.

@jmdavis
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Without that, how can much in the way of member functions be pure?

@yebblies
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@WalterBright
With the weak purity rules, functions should be able to do anything they like with any passed in parameters, including the implicit this parameter. Their only restriction is they they cannot directly access non-immutable global variables directly. They can even access globals if they are passed a pointer to them.
Purity isn't violated as strong-pure functions would never be able to pass global data into weak pure functions anyway.

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