On 11/16/2014 01:28 PM, musikbear wrote:
> great info!
> Could you point to a 'model-example' in the code, where this is 'Signal &
> slots' is used in the correct way -like
> xxx.h
> line : xyz
I can point to a correct and incorrect usage in the same file.
BassBoosterControls.cpp
lines 40-42: bad usage.
connect( &m_freqModel, SIGNAL( dataChanged() ), this, SLOT(
changeFrequency() ) );
connect( &m_gainModel, SIGNAL( dataChanged() ), this, SLOT(
changeGain() ) );
connect( &m_ratioModel, SIGNAL( dataChanged() ), this, SLOT(
changeRatio() ) );
Here, the signals generated by AutomatableModel are connected to slots
in the effect. This is bad, because it causes a costly operation each
time a value of a knob is changed. Instead, the effect should track the
changes in some other way, eg. manually checking if the values are
changed and acting accordingly.
This kind of incorrect usage is very common in our codebase. Perhaps
AutomatableModel needs a method to check for changed values, eg.
AutomatableModel::valueChanged(), which would return true if the value
has changed since last period. This could then be used by all DSP that
needs to react to value changes in some way.
line 43: good usage.
connect( engine::mixer(), SIGNAL( sampleRateChanged() ), this, SLOT(
changeFrequency() ) );
Here, we're connecting samplerate change to a slot in the effect. This
is fine, because sample rate changes happen so infrequently and never at
a speed-critical time, so they don't cause any performance loss.
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