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Use inherited accessors on instances instead of own properties.
(Split out scope chain objects into their own reflection type, Debug.Environment. Other changes.) |
(Use inherited accessors on instances instead of own properties.) |
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=== Properties === | === Properties === | ||
Properties of objects the <code>Debug</code> interface creates, and those of the interface objects themselves, follow some general conventions: | |||
<ul> | <ul> | ||
<li>Properties | <li>Instances and prototypes are extensible; you can add your own properties and methods to them. | ||
<li>Properties are configurable. This applies to both "own" and prototype properties, and to both methods and data properties. (Leaving these properties open to redefinition will hopefully make it easier for JavaScript debugger code to cope with bugs, bug fixes, and changes in the interface over time.) | |||
<li>Method properties are writable. | <li>Method properties are writable. | ||
<li> | <li>We prefer inherited accessor properties to own data properties. Both are read using the same syntax, but inherited accessors seem like a more accurate reflection of what's going on. Unless otherwise noted, these properties have getters but no setters, as they cannot meaningfully be assigned to. | ||
</ul> | </ul> | ||
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</dl> | </dl> | ||
== | == The Debug Object == | ||
To begin debugging another compartment's code, create a Debug object for the debuggee compartment. You can use this object to install hook functions, set breakpoints, and so on. | To begin debugging another compartment's code, create a Debug object for the debuggee compartment. You can use this object to install hook functions, set breakpoints, and so on. | ||
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</dl> | </dl> | ||
=== Properties of Debug | === Accessor Properties of the Debug Prototype Object === | ||
A <code>Debug</code> instance inherits the following accessor properties from its prototype: | |||
<dl> | <dl> | ||
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</dl> | </dl> | ||
=== Properties of the Debug Prototype Object === | === Function Properties of the Debug Prototype Object === | ||
The functions described below may only be called with a <code>this</code> value referring to a <code>Debug</code> instance; they may not be used as methods of other kinds of objects. | The functions described below may only be called with a <code>this</code> value referring to a <code>Debug</code> instance; they may not be used as methods of other kinds of objects. | ||
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A <code>Debug.Frame</code> instance is a weak reference to the frame; once the debuggee destroys the frame (by returning from the function, completing the <code>eval</code> call, freeing the generator-iterator object, or taking some similar action), the <code>Debug.Frame</code> instance becomes inactive: its <code>live</code> property becomes <code>false</code>, its properties become undefined, and calls to its methods throw exceptions. (Note that this means that debugger code can be affected by the garbage collector, since debugger code can notice when <code>Debug.Frame</code> instances die.) | A <code>Debug.Frame</code> instance is a weak reference to the frame; once the debuggee destroys the frame (by returning from the function, completing the <code>eval</code> call, freeing the generator-iterator object, or taking some similar action), the <code>Debug.Frame</code> instance becomes inactive: its <code>live</code> property becomes <code>false</code>, its properties become undefined, and calls to its methods throw exceptions. (Note that this means that debugger code can be affected by the garbage collector, since debugger code can notice when <code>Debug.Frame</code> instances die.) | ||
=== Properties of Debug.Frame | === Accessor Properties of the Debug.Frame Prototype Object === | ||
A <code>Debug.Frame</code> instance | A <code>Debug.Frame</code> instance inherits the following accessor properties from its prototype: | ||
<dl> | <dl> | ||
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</dl> | </dl> | ||
=== Properties of the Debug.Frame Prototype Object === | === Function Properties of the Debug.Frame Prototype Object === | ||
The functions described below may only be called with a <code>this</code> value referring to a <code>Debug.Frame</code> instance; they may not be used as methods of other kinds of objects. | The functions described below may only be called with a <code>this</code> value referring to a <code>Debug.Frame</code> instance; they may not be used as methods of other kinds of objects. | ||
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The lifetime of a script depends on its origin. A function script is shared by all closures produced for that function, and lives as long as there are live closures referring to it. An <code>eval</code> script lives until the call to <code>eval</code> completes. Debuggers should avoid depending on scripts' lifetimes after the stack frames, functions, and so on that own them have been destroyed. | The lifetime of a script depends on its origin. A function script is shared by all closures produced for that function, and lives as long as there are live closures referring to it. An <code>eval</code> script lives until the call to <code>eval</code> completes. Debuggers should avoid depending on scripts' lifetimes after the stack frames, functions, and so on that own them have been destroyed. | ||
=== Properties of Debug.Script | === Accessor Properties of the Debug.Script Prototype Object === | ||
<dl> | <dl> | ||
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</dl> | </dl> | ||
=== Properties of the Debug.Script Prototype Object === | === Function Properties of the Debug.Script Prototype Object === | ||
The functions described below may only be called with a <code>this</code> value referring to a <code>Debug.Script</code> instance; they may not be used as methods of other kinds of objects. | The functions described below may only be called with a <code>this</code> value referring to a <code>Debug.Script</code> instance; they may not be used as methods of other kinds of objects. | ||
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<code>Debug.Environment</code> instances protect their referents from the garbage collector; as long as the <code>Debug.Environment</code> instance is live, the referent remains live. Garbage collection has no debugger-visible effect on <code>Debug.Environment</code> instances. | <code>Debug.Environment</code> instances protect their referents from the garbage collector; as long as the <code>Debug.Environment</code> instance is live, the referent remains live. Garbage collection has no debugger-visible effect on <code>Debug.Environment</code> instances. | ||
=== | === Accessor Properties of the Debug.Environment Prototype Object === | ||
A <code>Debug.Environment</code> instance inherits the following accessor properties from its prototype: | |||
<dl> | <dl> | ||
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</dl> | </dl> | ||
=== Properties of the Debug.Environment Prototype Object === | === Function Properties of the Debug.Environment Prototype Object === | ||
The methods described below may only be called with a <code>this</code> value referring to a <code>Debug.Environment</code> instance; they may not be used as methods of other kinds of objects. | The methods described below may only be called with a <code>this</code> value referring to a <code>Debug.Environment</code> instance; they may not be used as methods of other kinds of objects. | ||