I have not looked at the gawk code (and for legal reasons choose not to do so). But one might guess that a function named set_NF() would set the value of the awk NF variable. Are you really telling me that gawk sets the value of NF for a new input record BEFORE parsing that record into fields??? That makes absolutely no sense to me! How can it set NF before it parses a record into fields to determine what value should be assigned to NF? One might expect that a function like that would be called to parse an input line or AFTER parsing an input line depending on the context. In the context of reading a new record from an input file at the start of a new cycle and in the context of using the awk command:

Code:

getline

with no argument naming a variable to be assigned and with no input redirection that should happen (as well as setting $x (for 0 <= x <= NF), NR, and FNR). In the context of reading a new record from an input file using the awk command:

Code:

getline variable

with a variable, but no input redirection, NR and FNR should be updated, but NF and the current record's fields should not be modified. In the context of reading a new record from an input file using the awk command:

Code:

getline variable < file
        or
command | getline variable

with a variable and with input redirection, none of the variables NF, NR, FNR, nor the current record's fields should change.