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Modules getting properties instead of fields?
f#

I bumped into this weird (from my point of view at least, there is probably a really good reason for it) thing today while playing around with reflector and the DLLs generated by the F# compiler, assume this very basic snippet of F#

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module Foo

let mutable private bar = 1

[b]Gets generated as this:[/b]

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[CompilationMapping(SourceConstructFlags.Module)]

public static class Foo

{

    // Properties

    [CompilationMapping(SourceConstructFlags.Value)]

    internal static int bar

    {

        get

        {

            return $Foo.bar@3;

        }

        set

        {

            $Foo.bar@3 = value;

        }

    }

}

internal static class $Foo

{

    // Fields

    [DebuggerBrowsable(DebuggerBrowsableState.Never)]

    internal static int bar@3 = 1;

    [DebuggerBrowsable(DebuggerBrowsableState.Never), CompilerGenerated, DebuggerNonUserCode]

    internal static int init@;

}

From my point of view, this seems redundant. Why not generate the field directly on the static class representing the module, instead of getting one extra level of indirection (and thus, slow down) by going through a property?

.

I can't comment as to why this code generation strategy is used, but you shouldn't have to worry about performance. Short methods such as those getters and setters will generally be inlined by the runtime's JIT compiler, so there's no penalty for not using fields directly (the generated machine code should be identical).

By on 3/22/2010 8:23 AM ()

There will probably be a performance penalty if the type of the field is a large struct type. There are also other situations where the .NET JITs don't inline small methods perfectly.

By on 3/24/2010 6:33 AM ()

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