Question: p expression

aris · July 5, 2012, 10:29am

Lately I have been going through some Ruby books and I keep coming up on
an script like the following:

hash={“A”=>10, “B”=>20, “C”=>30}
p hash.keys() # what is this

What is this p method or expression I keep coming across? I understand
that this is some kind of print statement, but that is all I understand
about this statement.
I have tried doing a google search, but since I cannot defined what
this expression is I have not found a vaild result. Can someone please
explain what this [p] expression or method is??

Happy Coding

smoothedatol412 · July 5, 2012, 10:39am

On 07/05/2012 10:29 AM, smoothedatol412 @gmail.com wrote:

Lately I have been going through some Ruby books and I keep coming up on
an script like the following:

hash={“A”=>10, “B”=>20, “C”=>30}
p hash.keys() # what is this

What is this p method or expression I keep coming across?

[1] pry(main)> method(:p)
=> #<Method: Object(Kernel)#p>

smoothedatol412 · July 5, 2012, 10:57am

So are the following two statements equivalent?

puts object.insect()
p object

Its just a short hand version of [puts object.insect()]? I want to ask
but I start using it in notes or in code, and I have been learning or
thing its one thing when it is another…

smoothedatol412 · July 5, 2012, 12:14pm

2012/7/5 smoothedatol412 @gmail.com [email protected]:

So are the following two statements equivalent?

puts object.insect()
p object

Basically, yes.

– Matma R.

smoothedatol412 · July 5, 2012, 12:25pm

Thanks alot

smoothedatol412 · July 5, 2012, 10:40am

On Thu, Jul 5, 2012 at 10:29 AM, smoothedatol412 @gmail.com
[email protected] wrote:

this expression is I have not found a vaild result. Can someone please
explain what this [p] expression or method is??

Try “ri p” instead or http://rdoc.info/stdlib/core/frames

Cheers

robert

smoothedatol412 · July 5, 2012, 2:47pm

Not very useful

You can also do this in Pry:

[37] (pry) main: 0> ? p

From: io.c (C Method):
Number of lines: 11
Owner: Kernel
Visibility: private
Signature: p(*arg1)

For each object, directly writes
obj.inspect followed by the current output
record separator to the program’s standard output.

S = Struct.new(:name, :state)
s = S[‘dave’, ‘TX’]
p s

produces:

#<S name=“dave”, state=“TX”>
[38] (pry) main: 0> $ p

From: io.c (C Method):
Number of lines: 20
Owner: Kernel
Visibility: private

static VALUE
rb_f_p(int argc, VALUE *argv, VALUE self)
{
int i;
VALUE ret = Qnil;

for (i=0; i<argc; i++) {
rb_p(argv[i]);
}
if (argc == 1) {
ret = argv[0];
}
else if (argc > 1) {
ret = rb_ary_new4(argc, argv);
}
if (TYPE(rb_stdout) == T_FILE) {
rb_io_flush(rb_stdout);
}
return ret;

}
[39] (pry) main: 0>

Lars H. wrote in post #1067498:

On 07/05/2012 10:29 AM, smoothedatol412 @gmail.com wrote:

Lately I have been going through some Ruby books and I keep coming up on
an script like the following:

hash={“A”=>10, “B”=>20, “C”=>30}
p hash.keys() # what is this

What is this p method or expression I keep coming across?

[1] pry(main)> method(:p)
=> #<Method: Object(Kernel)#p>

Module: Kernel (Ruby 1.9.3)

smoothedatol412 · July 8, 2012, 11:39am

I did not know that people were still commenting this topic…
Anyways, I do not like the short hand version of using this type of
statement in ruby when I tried to use it in test scripts.

short example

var=10
p var

I have choose to use the following statement instead

var=10
puts var.inspect()

I have come from Java and a few other programming backgrounds and I am
use to the compiled langs, like C and Java. I like coding things
out the long way since it is easy to go back later on and easily find
that bug code that is creating problems for the program.

smoothedatol412 · July 9, 2012, 8:09am

On Sun, Jul 8, 2012 at 11:39 AM, smoothedatol412 @gmail.com
[email protected] wrote:

var=10
puts var.inspect()

I have come from Java and a few other programming backgrounds and I am
use to the compiled langs, like C and Java. I like coding things
out the long way since it is easy to go back later on and easily find
that bug code that is creating problems for the program.

While I generally sympathize with that approach (making things
explicit) I don’t agree in this particular case. You’ll find “p var”
as easily as “puts var.inspect” - but it’s far less typing.

Cheers

robert

smoothedatol412 · July 6, 2012, 9:42pm

On Thu, Jul 5, 2012 at 3:14 AM, Bartosz Dziewoński [email protected]
wrote:

So are the following two statements equivalent?

puts object.inspect()
p object

Basically, yes.