use memory size prefixes consistently about dd HOT 2 CLOSED

Above (#77 (comment)), the conclusion was to, among other changes, rename the constants dd.cudd.GB and dd.cudd_zdd.GB to dd.cudd.GiB and dd.cudd_zdd.GiB, respectively (and to remove the unused constant dd.sylvan.GB).

Previously, in each of these two modules, the constant GB was used at two places, and only internally to dd (the constant could have been hidden as _GB). However, the changes described above would result in the constant GiB being used at only one place (and still only internally to dd): just to define another constant, on the line after the line that would define GiB. So the constant GiB would be redundant ("Simple is better than complex." PEP 20).

Therefore, the constant GB will be removed from these modules, and no replacement constant (like GiB was intended to be) added. Instead, the number 2**30 will replace the use of GB on the line this occurs. A comment will mention "GiB" and the relevant standard, in order to emphasize that the chosen number (2**30) is a binary multiple. This removes entirely from dd the presence of any convention on naming multiples: the numbers themselves are used directly.

Also, several of the concerns and alternatives discussed regarding the renaming are not relevant or applicable after this decision, so it becomes obvious what the new design will be.

Aside: A module variable that is intended to be used as a constant is usually named with all uppercase letters and underscores, according to PEP 8. So the choice of identifier GiB above would not have been entirely incompatible with PEP 8, though it is not recommended (nevertheless, this naming case concerns a standardized unit name, so preserving the letter case seems the best choice). In any case, the decision to remove the constant as unnecessary also avoids this naming conundrum.

from dd.

Addressed in commits cc8a609, e248d95, a1dbbd6, and 4f488a3.

from dd.