|
|
|
6.9 BlockClosure
- Defined in namespace Smalltalk
- Category: Language-Implementation
- I am a factotum class. My instances represent Smalltalk blocks, portions
of executeable code that have access to the environment that they were
declared in, take parameters, and can be passed around as objects to be
executed by methods outside the current class.
Block closures are sent a message to compute their value and create a new
execution context; this property can be used in the construction of
control flow methods. They also provide some methods that are used in the
creation of Processes from blocks.
6.9.1 BlockClosure class: instance creation
- block: aCompiledBlock
- Answer a BlockClosure that activates the passed CompiledBlock.
- numArgs: args numTemps: temps bytecodes: bytecodes depth: depth literals: literalArray
- Answer a BlockClosure for a new CompiledBlock that is created using the passed parameters. To make it work, you must put the BlockClosure into a CompiledMethod's literals.
6.9.2 BlockClosure class: testing
- isImmediate
- Answer whether, if x is an instance of the receiver, x copy == x
6.9.3 BlockClosure: accessing
- argumentCount
- Answer the number of arguments passed to the receiver
- block
- Answer the CompiledBlock which contains the receiver's bytecodes
- block: aCompiledBlock
- Set the CompiledBlock which contains the receiver's bytecodes
- finalIP
- Answer the last instruction that can be executed by the receiver
- fixTemps
- This should fix the values of the temporary variables used in the block that are ordinarily shared with the method in which the block is defined. Not defined yet, but it is not harmful that it isn't. Answer the receiver.
- initialIP
- Answer the initial instruction pointer into the receiver.
- method
- Answer the CompiledMethod in which the receiver lies
- numArgs
- Answer the number of arguments passed to the receiver
- numTemps
- Answer the number of temporary variables used by the receiver
- outerContext
- Answer the method/block context which is the immediate outer of the receiver
- outerContext: containingContext
- Set the method/block context which is the immediate outer of the receiver
- receiver
- Answer the object that is used as `self' when executing the receiver (if nil, it might mean that the receiver is not valid though...)
- receiver: anObject
- Set the object that is used as `self' when executing the receiver
- stackDepth
- Answer the number of stack slots needed for the receiver
6.9.4 BlockClosure: built ins
- blockCopy: outerContext
- Generate a BlockClosure identical to the receiver, with the given context as its outer context.
- value
- Evaluate the receiver passing no parameters
- value: arg1
- Evaluate the receiver passing arg1 as the only parameter
- value: arg1 value: arg2
- Evaluate the receiver passing arg1 and arg2 as the parameters
- value: arg1 value: arg2 value: arg3
- Evaluate the receiver passing arg1, arg2 and arg3 as the parameters
- valueWithArguments: argumentsArray
- Evaluate the receiver passing argArray's elements as the parameters
6.9.5 BlockClosure: control structures
- repeat
- Evaluate the receiver 'forever' (actually until a return is executed or the process is terminated).
- whileFalse
- Evaluate the receiver until it returns true
- whileFalse: aBlock
- Evaluate the receiver. If it returns false, evaluate aBlock and re- start
- whileTrue
- Evaluate the receiver until it returns false
- whileTrue: aBlock
- Evaluate the receiver. If it returns true, evaluate aBlock and re- start
6.9.6 BlockClosure: exception handling
- ensure: aBlock
- Evaluate the receiver; when any exception is signaled exit returning the result of evaluating aBlock; if no exception is raised, return the result of evaluating aBlock when the receiver has ended
- ifCurtailed: aBlock
- Evaluate the receiver; when any exception is signaled exit returning the result of evaluating aBlock; if no exception is raised, return the result of evaluating the receiver
- ifError: aBlock
- Evaluate the receiver; when #error: is called, pass to aBlock the receiver and the parameter, and answer the result of evaluating aBlock. If another exception is raised, it is passed to an outer handler; if no exception is raised, the result of evaluating the receiver is returned.
- on: anException do: aBlock
- Evaluate the receiver; when anException is signaled, evaluate aBlock passing a Signal describing the exception. Answer either the result of evaluating the receiver or the parameter of a Signal>>#return:
- on: e1 do: b1 on: e2 do: b2
- Evaluate the receiver; when e1 or e2 are signaled, evaluate respectively b1 or b2, passing a Signal describing the exception. Answer either the result of evaluating the receiver or the argument of a Signal>>#return:
- on: e1 do: b1 on: e2 do: b2 on: e3 do: b3
- Evaluate the receiver; when e1, e2 or e3 are signaled, evaluate respectively b1, b2 or b3, passing a Signal describing the exception. Answer either the result of evaluating the receiver or the parameter of a Signal>>#return:
- on: e1 do: b1 on: e2 do: b2 on: e3 do: b3 on: e4 do: b4
- Evaluate the receiver; when e1, e2, e3 or e4 are signaled, evaluate respectively b1, b2, b3 or b4, passing a Signal describing the exception. Answer either the result of evaluating the receiver or the parameter of a Signal>>#return:
- on: e1 do: b1 on: e2 do: b2 on: e3 do: b3 on: e4 do: b4 on: e5 do: b5
- Evaluate the receiver; when e1, e2, e3, e4 or e5 are signaled, evaluate respectively b1, b2, b3, b4 or b5, passing a Signal describing the exception. Answer either the result of evaluating the receiver or the parameter of a Signal>>#return:
- valueWithUnwind
- Evaluate the receiver. Any errors caused by the block will cause a backtrace, but execution will continue in the method that sent #valueWithUnwind, after that call. Example: [ 1 / 0 ] valueWithUnwind. 'unwind works!' printNl. Important: this method is public, but it is intended to be used in very special cases. You should usually rely on #ensure: and #on:do:
6.9.7 BlockClosure: multiple process
- fork
- Create a new process executing the receiver and start it
- forkAt: priority
- Create a new process executing the receiver with given priority and start it
- forkWithoutPreemption
- Evaluate the receiver in a process that cannot be preempted. If the receiver expect a parameter, pass the current process (can be useful for queuing interrupts from within the uninterruptible process).
- newProcess
- Create a new process executing the receiver in suspended state. The priority is the same as for the calling process. The receiver must not contain returns
- newProcessWith: anArray
- Create a new process executing the receiver with the passed arguments, and leave it in suspended state. The priority is the same as for the calling process. The receiver must not contain returns
- valueWithoutPreemption
- Evaluate the receiver without ever having it pre-empted by another process. This selector name is deprecated; use #forkWithoutPreemption instead.
6.9.8 BlockClosure: overriding
- deepCopy
- Answer the receiver.
- shallowCopy
- Answer the receiver.
6.9.9 BlockClosure: testing
- hasMethodReturn
- Answer whether the block contains a method return
|
