1. A non-transitory computer-readable medium holding instructions executable by a processor, the instructions comprising: instructions that, when executed, cause the processor to: interact with a graphical model that includes; a block, and a connection representing a signal received by or output from the block, wherein: the signal is associated with an attribute, the attribute represents a size or a dimensionality of the signal, and the size or the dimensionality of the signal changes during an execution of the graphical model; and generate code from the graphical model, the generated code comprising: code representing the connection, the code representing the connection implicitly conveying the size or the dimensionality of the signal, code representing the block, the code representing the block: identifying that the attribute of the signal representing the size or the dimensionality of the signal is a variable attribute, and retrieving or setting the size or the dimensionality of the signal using the attribute at a plurality of times during the execution of the model, the retrieving or the setting occurring before reading information from the connection or writing information to the connection.