Difference between revisions of "PERL/C3/Including-files-or-modules/English-timed"
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PoojaMoolya (Talk | contribs) (Created page with "{| Border = 1 |'''Time ''' |'''Narration''' |- |00:01 |Welcome to the''' Spoken Tutorial''' on''' Including files or modules in a PERL program''' |- |00:08 |In this tutorial...") |
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| − | |Do Method: These are simple ways to include the source code from other files into the current script file. | + | |'''Do Method''': These are simple ways to include the source code from other files into the current script file. |
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|00:57 | |00:57 | ||
| − | |Open a new file in your text editor and name it as '''datetime | + | |Open a new file in your text editor and name it as '''datetime dot pl''' |
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|04:05 | |04:05 | ||
| − | |We will write another '''Perl''' script where we’ll use this''' sum | + | |We will write another '''Perl''' script where we’ll use this''' sum dot pm''' file. |
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| 04:11 | | 04:11 | ||
| − | | Let me open the sample program app dot pl file which I have saved already | + | | Let me open the sample program '''app dot pl''' file which I have saved already |
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|05:10 | |05:10 | ||
| − | |Let us see few more options in''' use method'''. Switch back to''' sum | + | |Let us see few more options in''' use method'''. Switch back to''' sum dot pm '''in the '''text editor.''' |
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|06:41 | |06:41 | ||
| − | |Let me open the sample program''' commonfunctions | + | |Let me open the sample program''' commonfunctions dot pl''' which I have already saved. |
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|08:02 | |08:02 | ||
| − | |'''require''' reads the''' commonfunctions | + | |'''require''' reads the''' commonfunctions dot pl''' file containing '''Perl''' code and compiles it. |
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| − | |The value is stored in''' $number.''' | + | |The value is stored in''' $number.''' The value is to passed to the function''' square''' in''' commonfunctions dot pl''' file. |
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| − | |08:47 | + | |08:47 |
|The '''print statement''' prints the square of a number as output. | |The '''print statement''' prints the square of a number as output. | ||
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|09:20 | |09:20 | ||
| − | |Note that in this program we have called only three functions out of four from '''commonfunctions | + | |Note that in this program we have called only three functions out of four from '''commonfunctions dot pl'''. |
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|09:28 | |09:28 | ||
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|10:33 | |10:33 | ||
| − | |Here is an assignment for you. | + | |Here is an assignment for you. Write a''' Perl''' program''' reminder.pl''' where you will write a letter to the participants. |
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|10:45 | |10:45 | ||
| − | |Call the subroutines from''' Letter | + | |Call the subroutines from''' Letter dot pm''' using '''‘use’''' method. |
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|10:50 | |10:50 | ||
| − | | Write the below functions in''' Letter | + | | Write the below functions in''' Letter dot pm '''file. |
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|10:54 | |10:54 | ||
| − | | LetterDate() function returns the current date and time | + | | '''LetterDate()''' function returns the current date and time |
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|10:58 | |10:58 | ||
| − | |To() function returns the name of the participants | + | |'''To()''' function returns the name of the participants |
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|11:02 | |11:02 | ||
| − | | From() function returns the sender name | + | | '''From()''' function returns the sender name |
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|11:05 | |11:05 | ||
| − | | Lettermsg() function returns the content of the letter | + | |''' Lettermsg()''' function returns the content of the letter |
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|11:09 | |11:09 | ||
| − | |Thanksmsg() function returns thanks and regards. | + | |'''Thanksmsg()''' function returns thanks and regards. |
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Revision as of 15:53, 26 November 2015
| Time | Narration |
| 00:01 | Welcome to the Spoken Tutorial on Including files or modules in a PERL program |
| 00:08 | In this tutorial we will learn to use
methods in PERL programming. |
| 00:16 | For this tutorial, I am using
|
| 00:28 | You can use any text editor of your choice. |
| 00:32 | To follow this tutorial, you should have working knowledge of Perl programming. |
| 00:37 | If not, then go through the relevant Perl spoken tutorials on the spoken tutorial website. |
| 00:44 | Do Method: These are simple ways to include the source code from other files into the current script file. |
| 00:53 | Let us understand how to use do() method. |
| 00:57 | Open a new file in your text editor and name it as datetime dot pl |
| 01:03 | In the datetime dot pl file, type the following code as displayed on the screen. |
| 01:09 | From here onwards, remember to press the Enter key after every command on the terminal. |
| 01:15 | Let us understand the code now. |
| 01:18 | The current date and time is stored in a variable dollar datestring. |
| 01:23 | Here, I have a function by name msgThanks, which returns a “Thank you” message. |
| 01:31 | Now, press Ctrl+S to save the file. |
| 01:35 | Next let us look at another Perl program which will make use of this file datetime dot pl |
| 01:43 | Open a new file in your text editor and name it as main dot pl |
| 01:49 | In the main dot pl file, type the following code as displayed on the screen. |
| 01:55 | Let me explain the code now. |
| 01:58 | Here, the first line prints the welcome message. |
| 02:03 | do() method is called with the filename from where we want to use the code. |
| 02:09 | Current date and time is stored in the $datestring variable of datetime dot pl file. |
| 02:16 | And at the end, we call the msgThanks() function from the same file. |
| 02:21 | Now, press Ctrl+S to save the file. |
| 02:25 | Let us execute the program. |
| 02:27 | Switch back to the terminal and type perl main dot pl and press Enter |
| 02:34 | Observe the output on the terminal. |
| 02:37 | Next we will learn how to use require method and use method in a Perl program. |
| 02:44 | These methods are used - when we have collections of subroutines that can be used in multiple Perl programs. |
| 02:52 | use method is used only for the modules. |
| 02:56 | It is verified at the time of compilation |
| 02:59 | There is no need to give the file extension |
| 03:03 | require method is used for both Perl programs and modules |
| 03:08 | It is verified at the run time |
| 03:10 | One needs to give the file extension. |
| 03:14 | The syntax of use method is use module name semicolon |
| 03:20 | Perl modules are the files which end with .pm extension. |
| 03:25 | Reusability of code is implemented through modules. |
| 03:30 | These are similar to libraries in other languages. |
| 03:35 | Now I will show a simple program with the use method to include a module in Perl code. |
| 03:43 | Open a new file In your text editor and name it as sum dot pm. |
| 03:49 | In the sum dot pm file, type the following code as displayed on the screen. |
| 03:55 | Here, I have a simple function which will calculate the sum of a given set of numbers. |
| 04:01 | Now, press Ctrl+S to save the file |
| 04:05 | We will write another Perl script where we’ll use this sum dot pm file. |
| 04:11 | Let me open the sample program app dot pl file which I have saved already |
| 04:17 | In the app dot pl file, type the following code as displayed on the screen. |
| 04:22 | Let me explain the code now. |
| 04:25 | The first line shows the use method with the module name. |
| 04:29 | In our case, the module name is sum. |
| 04:33 | We are passing 1,7,5,4,9 as input parameters to the function total in sum dot pm file. |
| 04:44 | Again, in the next line, we are passing 1 to 10 as input parameters to the same function. |
| 04:52 | Now, press Ctrl+S to save the file. |
| 04:56 | Let us execute the program. |
| 04:59 | Switch back to the terminal and type perl app dot pl and Press Enter |
| 05:06 | Observe the output displayed on the terminal. |
| 05:10 | Let us see few more options in use method. Switch back to sum dot pm in the text editor. |
| 05:18 | At the beginning of the source code, add the lines use strict semicolon use warnings semicolon |
| 05:27 | use strict and use warnings are compiler flags that instruct Perl to behave in a stricter way. |
| 05:35 | These are used to avoid common programming mistakes. |
| 05:39 | use strict forces the user to declare all the variables used in the program. |
| 05:45 | If there are errors, use strict will abort the execution. |
| 05:50 | use warnings will only provide warnings but continue with the execution. |
| 05:56 | Assume that we forgot to declare the variable $sum as my. |
| 06:02 | Let us now see how the same program is executed. |
| 06:06 | Press Ctrl+S to save the file. |
| 06:09 | Switch back to the terminal and type perl app dot pl |
| 06:15 | We can see that the program is aborted without executing the result. |
| 06:21 | The first set of lines displayed on the terminal are error messages generated by “use strict”. |
| 06:29 | The last two are the abort messages. |
| 06:32 | So, this is how the use method options work. |
| 06:36 | Next let us see a Perl program where we use the require method. |
| 06:41 | Let me open the sample program commonfunctions dot pl which I have already saved. |
| 06:48 | Type the following code as displayed on the screen in your commonfunctions dot pl file.
Let us understand the code now. |
| 06:57 | Here we can see a collection of commonly used functions. |
| 07:01 | The first function square() returns the square of a number. |
| 07:06 | The second function square underscore root() returns the square root of a given number. |
| 07:12 | Next function random underscore number() generates a random number. |
| 07:18 | The last function random underscore range() generates a random number between a lower range and upper range of numbers. |
| 07:26 | Note that we need the 1 semicolon at the end of the file. |
| 07:31 | This is because Perl needs the last expression in the file to return a true value. |
| 07:37 | Now, press Ctrl+S to save the file. |
| 07:41 | Next we will write a Perl program in which we’ll call these subroutines using require method. |
| 07:48 | Let me open the sample program callprogram dot pl which I have already saved. |
| 07:54 | Type the following code as displayed on the screen in your file. Let me explain the code now. |
| 08:02 | require reads the commonfunctions dot pl file containing Perl code and compiles it. |
| 08:09 | This program gives 4 options to the user. The user has to choose one option at a time. |
| 08:17 | One is to find the square of a number. |
| 08:20 | Two is for square root of a number. |
| 08:23 | Three is for a random number in the given range. Four is to quit the program. |
| 08:29 | If option one is typed, it will ask the user to enter a number. |
| 08:34 | The value is stored in $number. The value is to passed to the function square in commonfunctions dot pl file. |
| 08:44 | The function returns the square of a number. |
| 08:47 | The print statement prints the square of a number as output. |
| 08:52 | If option two is typed, the square root of a number is displayed as output. |
| 08:58 | The execution is followed as explained in the previous function square. |
| 09:03 | If option three is typed, a random number is displayed as output in the given range. |
| 09:09 | Else if option is four, the program exits. If any option other than the ones specified is given, the print statement says “Incorrect option”. |
| 09:20 | Note that in this program we have called only three functions out of four from commonfunctions dot pl. |
| 09:28 | Now, press Ctrl+S to save the file |
| 09:31 | Let us execute the program. |
| 09:34 | Switch back to the terminal and type perl callprogram dot pl |
| 09:41 | Observe the output |
| 09:44 | I'll execute the program once again with a different option. |
| 09:49 | Type perl callprogram dot pl |
| 09:53 | Now, Enter the Option as 3. |
| 09:56 | Enter a lower range as 50. |
| 09:59 | Enter a upper range as 99. |
| 10:02 | We can see the random number is generated in the given range of numbers. |
| 10:08 | Try other options on your own. |
| 10:11 | This brings us to the end of this tutorial. Let us summarise. |
| 10:16 | In this tutorial we learnt to use
|
| 10:24 | Note: "use Module" is recommended over "require Module", because it determines module availability at compile time. |
| 10:33 | Here is an assignment for you. Write a Perl program reminder.pl where you will write a letter to the participants. |
| 10:41 | Prompt the user to enter To and From name |
| 10:45 | Call the subroutines from Letter dot pm using ‘use’ method. |
| 10:50 | Write the below functions in Letter dot pm file. |
| 10:54 | LetterDate() function returns the current date and time |
| 10:58 | To() function returns the name of the participants |
| 11:02 | From() function returns the sender name |
| 11:05 | Lettermsg() function returns the content of the letter |
| 11:09 | Thanksmsg() function returns thanks and regards. |
| 11:13 | The output should be displayed as shown here. |
| 11:20 | The video at the following link summarize the spoken tutotial project. Please download and watch it |
| 11:27 | The Spoken Tutorial Project Team
|
| 11:36 | For more details, please write to us. |
| 11:40 | Spoken Tutorial project is funded by NMEICT, MHRD, Government of India.
More information on this mission is available at this link. |
| 11:51 | This is Nirmala Venkat from IIT Bombay, signing off. Thanks for watching. |
