Determining gnuradio block input and output types directly from block

Question

I know that from their input and output signatures, it's possible to determine the size of a gnuradio block's input and output items. I am wondering whether it's also possible to directly determine input and output type (float vs complex etc) from a block.

Answer 1

Within the GNU Radio runtime, only the size is stored. Type information only exists in the source code, and in GNU Radio Companion if you are using that.

So, no, you cannot get type information from a block object that already exists — except by imperfect outside-information strategies like looking up the block's name in the installed GRC data files to guess what the type is.

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Because there are no types but only sizes, items can be reinterpreted if they are the same size, which may occasionally be useful; for example, you can connect a block producing "complex" to one expecting "vector of 2 floats" and get a useful result since a complex is represented as two floats.