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51 lines
1.9 KiB
51 lines
1.9 KiB
name: duk_compact
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proto: |
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void duk_compact(duk_context *ctx, duk_idx_t obj_idx);
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summary: |
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<p>
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Resizes an object's internal memory allocation to minimize memory usage.
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If the value at <code>obj_idx</code> is not an object, does nothing.
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Although compaction is normally safe, it can fail due to an internal error
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(such as out-of-memory error). Compaction only affects to an object's
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"own properties", not its inherited properties.
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</p>
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<p>
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Compaction is not a final operation and has no impact on object semantics.
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Adding new properties to the object is still possible (assuming the object
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is extensible), but causes an object resize. Existing property values can be
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changed (assuming the properties are writable) without affecting the object's
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internal memory allocation. An object can be compacted multiple times:
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for instance, if a new property is added to a previously compacted object,
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the object can be compacted again to minimize memory footprint after the
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property addition.
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</p>
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<p>
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Compacting an object saves a small amount of memory per object. It is
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generally useful when (1) memory footprint is very important, (2) an object
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is unlikely to gain new properties, (3) an object is relatively long-lived,
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and (4) when compaction can be applied to enough many objects to make a
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significant difference.
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</p>
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<p>
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If <code>Object.seal()</code>, <code>Object.freeze()</code>, or
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<code>Object.preventExtensions()</code> is called, an object is automatically
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compacted.
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</p>
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example: |
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duk_push_object(ctx); /* [ ... obj ] */
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duk_push_int(ctx, 42); /* [ ... obj 42 ] */
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duk_put_prop_string(ctx, -2, "meaningOfLife"); /* [ ... obj ] */
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duk_compact(ctx, -1); /* [ ... obj ] */
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tags:
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- object
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- property
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- memory
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introduced: 1.0.0
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