Re: multiple plot lines with plot '-'

[<pl...@pi...>]

On 05/18/12 22:49, Ethan A Merritt wrote:
> On Friday, May 18, 2012 02:25:15 am pl...@pi... wrote:
>> If you are suggesting that associating a file descriptor with a file;
>> opening; reading; closing; reopening (with implies a seek(0) ) ; and
>> rereading   is the same as opening ; reading upto 'e' marker *in the
>> data* then continuing to read the same opened device,  I have to say
>> your reasoning is getting a bit contrived.
>>
>> I find it hard to see that as being the same behaviour.
>
> Nevertheless, from the point of view of the program itself, or of the
> programmers working on it, these cases are handled exactly the same way.
> You can find the code near the top of the routine df_open() in datafile.c
>
> In pseudocode:
>
>     if (*filename == '-')
> 		data_fp = stdin;
>     else if (*filename == '<')
> 		data_fp = fpopen( some piped command stored in filename );
>     else
> 		data_fp = fopen( filename );
>
> Other routines then read line by line from data_fp as needed.
> In two of the three cases, pipe and stdin, backing up to the beginning
> in order to re-read is not possible. The code never uses fseek().
>
> 	Ethan
>

stdin is already open, the other two cases call an open function. 
Calling fopen implicitly calls seek(0) as I pointed out earlier.

How are these "the same" ?

regards.