Question

我想查看键盘事件，根据Sensor的文档，我可以在不使用peekKeyboardEvent从队列中删除事件的情况下执行此操作，但它似乎无效。< / p>

这有效：

"Show that a single event can be checked multiple times"
Transcript clear; show: 'Type something... '; flush.
(Delay forSeconds: 2) wait.
5 timesRepeat: [  
    Transcript show: (Sensor peekEvent); cr
]

输出：

Type something... #(2 48243801 5 2 8 0 0 1)
#(2 48243801 5 2 8 0 0 1)
#(2 48243801 5 2 8 0 0 1)
#(2 48243801 5 2 8 0 0 1)
#(2 48243801 5 2 8 0 0 1)

但这不是：

"Show that a single keyboard event can be checked multiple times"
Transcript clear; show: 'Type something... '; flush.
(Delay forSeconds: 2) wait.
5 timesRepeat: [  
    Transcript show: (Sensor peekKeyboardEvent); cr
]

输出：

Type something... #(2 48205144 97 0 0 97 0 1)
nil
nil
nil
nil

另一个问题：为什么Transcript flush不会导致输出立即出现？它仅在脚本运行后出现。

Answer 1

首先，pharo是一个快速移动的目标，因此最好分辨哪个版本。

找到答案的最佳方法是浏览代码。我将在当前的开发pharo 3.0中展示这一点如果你浏览peekKeyboardEvent的实现者（选择它然后Alt + m），你会在InputEventSensor中找到一个版本：

peekKeyboardEvent
    "Allows for use of old Sensor protocol to get at the keyboard,
    as when running kbdTest or the InterpreterSimulator in Morphic"

    ^eventQueue findFirst: [:buf | self isKbdEvent: buf]

如果您分析对eventQueue

的inst var引用

initialize
        "Initialize the receiver"
        super initialize.
        eventQueue := WaitfreeQueue new.
        ...snip...

然后浏览WaitfreeQueue（选择它然后Alt + b）

findFirst: aBlock
    "Note, this method only for backward compatibility. It duplicating the semantics of #nextOrNilSuchThat: completely.
    Use #nextOrNilSuchThat: instead "

    ^ self nextOrNilSuchThat: aBlock

然后：

nextOrNilSuchThat: aBlock
    "Fetch an object from queue that satisfies aBlock, skipping (but not removing) any intermediate objects.
    If no object has been found, answer <nil> and leave me intact.

    NOTA BENE:  aBlock can contain a non-local return (^).
    Found item is removed from queue    .

    If queue currently in the middle of extraction by other process, don't wait and return <nil> immediately"
    ...snip...

你可以信任评论，或者自己在代码中验证，这种方法正在消耗事件而不是偷看。

所以看来确实这种民意调查方式已被弃用并且在pharo

中失去了支持

无法在Smalltalk Pharo 2中多次查看键盘事件

1 个答案: