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POHow to get this Qt state machine to work?
 

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  1. POHow to get this Qt state machine to work?
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    <p>I have two widgets that can be checked, and a numeric entry field that should contain a value greater than zero. Whenever both widgets have been checked, and the numeric entry field contains a value greater than zero, a button should be enabled. I am struggling with defining a proper state machine for this situation. So far I have the following:</p> <pre><code>QStateMachine *machine = new QStateMachine(this); QState *buttonDisabled = new QState(QState::ParallelStates); buttonDisabled-&gt;assignProperty(ui_-&gt;button, "enabled", false); QState *a = new QState(buttonDisabled); QState *aUnchecked = new QState(a); QFinalState *aChecked = new QFinalState(a); aUnchecked-&gt;addTransition(wa, SIGNAL(checked()), aChecked); a-&gt;setInitialState(aUnchecked); QState *b = new QState(buttonDisabled); QState *bUnchecked = new QState(b); QFinalState *bChecked = new QFinalState(b); employeeUnchecked-&gt;addTransition(wb, SIGNAL(checked()), bChecked); b-&gt;setInitialState(bUnchecked); QState *weight = new QState(buttonDisabled); QState *weightZero = new QState(weight); QFinalState *weightGreaterThanZero = new QFinalState(weight); weightZero-&gt;addTransition(this, SIGNAL(validWeight()), weightGreaterThanZero); weight-&gt;setInitialState(weightZero); QState *buttonEnabled = new QState(); buttonEnabled-&gt;assignProperty(ui_-&gt;registerButton, "enabled", true); buttonDisabled-&gt;addTransition(buttonDisabled, SIGNAL(finished()), buttonEnabled); buttonEnabled-&gt;addTransition(this, SIGNAL(invalidWeight()), weightZero); machine-&gt;addState(registerButtonDisabled); machine-&gt;addState(registerButtonEnabled); machine-&gt;setInitialState(registerButtonDisabled); machine-&gt;start(); </code></pre> <p>The problem here is that the following transition:</p> <pre><code>buttonEnabled-&gt;addTransition(this, SIGNAL(invalidWeight()), weightZero); </code></pre> <p>causes all the child states in the <code>registerButtonDisabled</code> state to be reverted to their initial state. This is unwanted behaviour, as I want the <code>a</code> and <code>b</code> states to remain in the same state.</p> <p>How do I ensure that <code>a</code> and <code>b</code> remain in the same state? Is there another / better way this problem can be solved using state machines?</p> <hr> <p><strong>Note</strong>. There are a countless (arguably better) ways to solve this problem. However, I am only interested in a solution that uses a state machine. I think such a simple use case should be solvable using a simple state machine, right?</p>
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