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A follow up question to @Tricky comment: how do concurrent statements outside a process work then? Don't say also assume that the values are ready from 0s? e.g.
my_output <= '111111111' when data_ready = '1';
Or would i use the
after statement here?
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They work exactly as you expect the underlying hardware to work. This example is fairly pointless - as it would set the output to all 1s when some data_ready input is '1', so you've built a latch because it does not have an else clause.
The after keyword is purely for simulation. It has no meaning in a real circuit as absolute delay elements do not exist. They are meant to model the propogation delay that may occur in a real circuit. They will be removed for synthesis (with associated warnings). So unless you want them for modelling purposes, do not use them. If you have a synchronous design you will never need them.
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