    The ed Editor

    	This has always been the aspect of coding that new
    creators have most trouble with. It's what discourages most
    people from creating lots of stuff, in fact.

    	With Dead Souls, you can get away with avoiding ed
    most of the time, by using the QCS.

    	But to add special functions to your code, like
    magic items, smart NPC's (aka mobs), traps, hidden objects,
    etc, you need to use ed, if you're going to be editing inside
    the mud.

    	ed is a simple editing program. It is designed to
    work on a line-by-line basis, so it is called a "line editor".

    	Let's start by looking at, and editing, a small file.
    We've coded a sword, and we want to change its description
    from "short sword" to "plain sword":

    > cd /realms/cratylus/area/weap1) I changed my working directory to my area weapons dir
    /realms/cratylus/area/weap:
    > ls I listed the contents of that dir:
    /realms/cratylus/area/weap/:
     1   dagger.c        1   nco_sword.c~    1   std_sword.c~
     1   gsword.c        1   sharpsword.c    1   sword.c
     001 gsword.c~       1   staff.c
     1   nco_sword.c     1   std_sword.c

    > ed sword.c I ran the ed command on the file sword.c.
    /realms/cratylus/area/weap/sword.c, 641 bytes
    :n This makes the editor display line numbers next to the lines.
    number on, list off
    :1z This lists about 20 lines of text
      1  /*    /domains/Examples/weapon/sword.c
      2   *    from the Nightmare IV LPC Library
      3   *    a simple sword example, nothing fancy
      4   *    created by Descartes of Borg 950402
      5   */
      6
      7  #include <lib.h>
      8  #include <damage_types.h>
      9  #include <vendor_types.h>
     10
     11  inherit LIB_ITEM;
     12
     13  static void create() {
     14      item::create();
     15      SetKeyName("short sword");
     16      SetId( ({ "sword", "short sword" }) );
     17      SetAdjectives( ({ "short" }) );
     18      SetShort("a short sword");
     19      SetLong("A cheap and rather dull short sword.");
     20      SetMass(150);
     21      SetDollarCost(50);
     22      SetVendorType(VT_WEAPON);
    :z
     22      SetVendorType(VT_WEAPON);
     23      SetClass(20);
     24      SetDamageType(BLADE);
     25      SetWeaponType("blade");
     26  }
    :15 I displayed line 15
     15      SetKeyName("short sword");
    :15c I used 'c' to replace line 15
        15. * SetKeyName("plain sword"); I entered my replacement text
        16. * . I entered a single dot on a blank line
    :
     16      SetId( ({ "sword", "short sword" }) );
    :1z I listed about 20 lines, starting from line 1
      1  /*    /domains/Examples/weapon/sword.c
      2   *    from the Nightmare IV LPC Library
      3   *    a simple sword example, nothing fancy
      4   *    created by Descartes of Borg 950402
      5   */
      6
      7  #include <lib.h>
      8  #include <damage_types.h>
      9  #include <vendor_types.h>
     10
     11  inherit LIB_ITEM;
     12
     13  static void create() {
     14      item::create();
     15  SetKeyName("plain sword");
     16      SetId( ({ "sword", "short sword" }) );
     17      SetAdjectives( ({ "short" }) );
     18      SetShort("a short sword");
     19      SetLong("A cheap and rather dull short sword.");
     20      SetMass(150);
     21      SetDollarCost(50);
     22      SetVendorType(VT_WEAPON);
    :18 I displayed line 18
     18      SetShort("a short sword");
    :18c I started the replacement of line 18
        18. * SetShort("a plain sword"); I entered my replacement text
        19. * . I entered a single dot on a blank line
    :1z I displayed about 20 lines starting from line 1
      1  /*    /domains/Examples/weapon/sword.c
      2   *    from the Nightmare IV LPC Library
      3   *    a simple sword example, nothing fancy
      4   *    created by Descartes of Borg 950402
      5   */
      6
      7  #include <lib.h>
      8  #include <damage_types.h>
      9  #include <vendor_types.h>
     10
     11  inherit LIB_ITEM;
     12
     13  static void create() {
     14      item::create();
     15  SetKeyName("plain sword");
     16      SetId( ({ "sword", "short sword" }) );
     17      SetAdjectives( ({ "short" }) );
     18  SetShort("a plain sword");
     19      SetLong("A cheap and rather dull short sword.");
     20      SetMass(150);
     21      SetDollarCost(50);
     22      SetVendorType(VT_WEAPON);
    :x I saved and exited
    "/realms/cratylus/area/weap/sword.c" 26 lines 633 bytes
    Exit from ed.
    > update sword I loaded the file into memory
    /realms/cratylus/area/weap/sword: Ok

    Let's take this step by step:

    1) I changed my working directory to my area weapons dir: cd /realms/cratylus/area/weap

    2) I listed the contents of that dir:  ls

    3) I ran the ed command on the file sword.c: ed sword.c

    4) Within the editor, I issued the 'n' command. This makes the editor
       display line numbers next to the lines.

    5) Within the editor, I issued the '1z' command. What 'z' does is display
       about 20 lines of the file (the exact number depends on your screen
       settings. In my case it's 22). If you happen to be looking at line 1, it
       will display lines 1 through to about 20. If you happen to be looking
       at line 40, it will display from line 40 to about 60.
       	If you want to start looking at lines starting at line 15, you
       can issue the '15z' command, which basically means "display about 20
       lines starting at line 15".
       	In this case, I wanted to start from the beginning of the file,
       so I issued '1z'.

    6) '1z' stopped listing the file at line 22, so I entered 'z' again to
        list the rest.

    7) Since I want to change "short sword" to "plain sword", I examined each
       line to find the word "short". I noticed that line 15 has "short" in it,
       so to get a look at that line alone, I entered '15'.

    8) Now that I'm sure line 15 needs to change, I issue the '15c' command.
       'c' indicates that I want to change a line. '15c' means "delete whatever
       was in line 15, and replace it with what I am about to type".

    9) You can see that my editor prompt changed from ":" to "*". What this
       means is that I am now in "input mode". Whatever I type now will be
       added to the file. Since my last command in "command mode" was '15c',
       I am now replacing that line with what I want the line to contain:
       SetKeyName("plain sword");

    10) Ok, I replaced the line, but I'm still in input mode. To go back to
        command mode, I type a single period and enter, like this:
        .

    11) I'm back in command mode now. When I list the file contents with
        '1z' I can see that line 15 now says what I wanted.

    12) Now I see another line that needs changing, so I enter '18' to
        get a closer look.

    13) Sure enough, 18 needs to change, so I issue '18c'.

    14) Like I did for line 15, I enter what the line should be.

    15) To return to command mode, I enter a single period on a blank line.

    16) I list the file contents, and see that my change was successful.

    17) I'm finished making my changes, so I issue the 'x' command. 'x'
        means "save the changes I have made, and exit the editor".

    18) I am now at my regular command prompt. To load my changes to this
        file, I type 'update sword'.

    Editor basics, part 2

    	In the last section you saw what a simple line
    replacement looks like in ed. Next we'll talk about some common
    ed actions.

    ADDING STUFF:

    	Suppose I want to specify that this sword requires only
    one hand to wield it:

    > ed sword.c started the editor
    /realms/cratylus/area/weap/sword.c, 633 bytes
    :n enabled line number printing
    number on, list off
    :15,22 listed lines 15 to 22
     15  SetKeyName("plain sword");
     16      SetId( ({ "sword", "short sword" }) );
     17      SetAdjectives( ({ "short" }) );
     18  SetShort("a plain sword");
     19      SetLong("A cheap and rather dull short sword.");
     20      SetMass(150);
     21      SetDollarCost(50);
     22      SetVendorType(VT_WEAPON);
    :20a appended to the file after line 20
        21. * SetHands(1); entered my added text
        22. * . single dot on a blank line to exit input mode
    :18,22 displayed line 18 through 22
     18  SetShort("a plain sword");
     19      SetLong("A cheap and rather dull short sword.");
     20      SetMass(150);
     21  SetHands(1);
     22      SetDollarCost(50);
    :x exited editor and saved
    "/realms/cratylus/area/weap/sword.c" 27 lines 646 bytes
    Exit from ed.

    	Here you can see that instead of 'c', which replaces, I
    used 'a', which adds. I decided my new line would go after line
    20, so I issued the command '20a'. Once I was done, I typed
    a single dot on a blank line to exit "input mode". You'll notice
    I didn't use the 'z' command. Instead, since I knew where my
    changes would go, I decided to list lines 18 through 22 with
    the command '18,22'. I then issued the 'x' command to save my
    changes and exit the editor.
    	If had I wanted my addition to go in front of line 20,
    I could have used the '20i' command.

    DELETING LINES

    	Suppose I'm tired of seeing header lines that no
    longer apply to this file. We can delete a single line, or
    a range of lines, with the 'd' commmand:

> ed sword.c

    /realms/cratylus/area/weap/sword.c, 646 bytes
    :n enabled line number printing
    number on, list off
    :1,10 listed lines 1 to 10
      1  /*    /domains/Examples/weapon/sword.c
      2   *    from the Nightmare IV LPC Library
      3   *    a simple sword example, nothing fancy
      4   *    created by Descartes of Borg 950402
      5   */
      6
      7  #include <lib.h>
      8  #include <damage_types.h>
      9  #include <vendor_types.h>
     10
    :1,5d deleted lines 1 to 5
    :1,5 listed (the new) lines 1 to 5
      1
      2  #include <lib.h>
      3  #include <damage_types.h>
      4  #include <vendor_types.h>
      5
    :1d deleted blank line 1
    :1z displayed the file starting at line 1
      1  #include <lib.h>
      2  #include <damage_types.h>
      3  #include <vendor_types.h>
      4
      5  inherit LIB_ITEM;
      6
      7  static void create() {
      8      item::create();
      9  SetKeyName("plain sword");
     10      SetId( ({ "sword", "short sword" }) );
     11      SetAdjectives( ({ "short" }) );
     12  SetShort("a plain sword");
     13      SetLong("A cheap and rather dull short sword.");
     14      SetMass(150);
     15  SetHands(1);
     16      SetDollarCost(50);
     17      SetVendorType(VT_WEAPON);
     18      SetClass(20);
     19      SetDamageType(BLADE);
     20      SetWeaponType("blade");
     21  }
    :x exited and saved
    "/realms/cratylus/area/weap/sword.c" 21 lines 476 bytes
    Exit from ed.

    	First I deleted lines 1 through 5 with the command '1,5d'.
    Then, for good measure, I removed the remaining blank line '1d'.
    	Voila. Cleaner code.

    REPLACING STRINGS

    	Well now I want to replace all instances of "short" with
    "plain", and I don't feel like editing each matching line
    manually. I can do a search and replace. First I will list which
    lines need to change, then I will change them:

> ed sword.c

    /realms/cratylus/area/weap/sword.c, 476 bytes
    :n enabled line number printing
    number on, list off
    :g/short/p  searched for and displayed lines containing "short"
     10      SetId( ({ "sword", "short sword" }) );
     11      SetAdjectives( ({ "short" }) );
     13      SetLong("A cheap and rather dull short sword.");
    :g/short/s/short/plain  searched for "short" and replaced with "plain"
    :g/short/p  searched for "short" again but found none
    :1z  listed file from line 1
      1  #include <lib.h>
      2  #include <damage_types.h>
      3  #include <vendor_types.h>
      4
      5  inherit LIB_ITEM;
      6
      7  static void create() {
      8      item::create();
      9  SetKeyName("plain sword");
     10      SetId( ({ "sword", "plain sword" }) );
     11      SetAdjectives( ({ "plain" }) );
     12  SetShort("a plain sword");
     13      SetLong("A cheap and rather dull plain sword.");
     14      SetMass(150);
     15  SetHands(1);
     16      SetDollarCost(50);
     17      SetVendorType(VT_WEAPON);
     18      SetClass(20);
     19      SetDamageType(BLADE);
     20      SetWeaponType("blade");
     21  }
    :1  moved to line 1
      1  #include <lib.h>
    :I  ran automatic indentation
    Indenting entire code...
    Indentation complete.
    :1z  listed file from line 1
    #include <lib.h>
    #include <damage_types.h>
    #include <vendor_types.h>

    inherit LIB_ITEM;

    static void create() {
        item::create();
        SetKeyName("plain sword");
        SetId( ({ "sword", "plain sword" }) );
        SetAdjectives( ({ "plain" }) );
        SetShort("a plain sword");
        SetLong("A cheap and rather dull plain sword.");
        SetMass(150);
        SetHands(1);
        SetDollarCost(50);
        SetVendorType(VT_WEAPON);
        SetClass(20);
        SetDamageType(BLADE);
        SetWeaponType("blade");
    }
    :x  exited and saved
    "/realms/cratylus/area/weap/sword.c" 21 lines 488 bytes
    Exit from ed.

    	The command g/short/p showed me all the lines
    that contained the substring "short". Then I ran the global
    search and replace command to substitute "plain" for "short",
    :g/short/s/short/plain
    	Then I searched again for the string "short" and
    nothing came up, because it had been replaced.

    	Finally I went to line number 1 and issued the 'I'
    command. This auto-indents the code, making it neater and
    easier to read.

    Editor basics, part 3

    Now let's look at some common problems:

    1) Accidental deletion

    	If you type 1,20d when you meant to type 1,2d you will end
    up with a file 18 lines shorter than you intended. ed does not
    have an "undo" command, so those lines will never come back.
    	However, if you quit the editor *without saving*, then that
    deletion will not be committed to the file. You can issue the 'Q'
    command:

    :Q

    	To force quit without saving. Of course, if those lines
    weren't already in the file, this won't help much.

    2) Can't leave the editor

    	You try to write and exit, but get this:

    :x
    File command failed.

    	What this means is that for some reason, you can't write
    to the file, so you don't exit the editor. What this usually means is that
    you tried to edit a file that does not belong to you. Since you do not
    have permission to modify the file, ed refuses to commit your changes.

    	There are two ways around this. If you don't really care
    whether your changes are saved or not, you can just force quit the
    editor with 'Q':

    :Q
    Exit from ed.

    	Your changes will be lost, but you'll be out of the editor.

    	If you really want to save this file, you'll have to save it
    somewhere other than your current working directory (cwd). You can save
    it to your home directory with the 'w' command, then force quit:

    :w /realms/cratylus/sword.c
    "/realms/cratylus/sword.c" 20 lines 478 bytes
    :Q
    Exit from ed.

    3) Indent command fails

    	You try to auto-indent your code but get an error like this:

    :I
    Indenting entire code...
    Unterminated string in line 13
    Indentation halted.

    	This is pretty self explanatory. Indent relies on a certain
    amount of coherence in your code, and if your syntax is sufficiently
    munged, it can't figure out how to properly do its thing.
    	Examine the line that indent complains about, and also the
    line before it. Sometimes a good line is accused of being bad, just
    because it comes after a bad line.

    4) I need to [something] in ed, but don't know how!

    	While in command mode, type 'h' and enter. You'll get
    a handy list of ed commands available to you.

    5) My ability/patience/time is limited. I want not to use ed.

    	I feel your pain. The currently available ways around
    this are:

    1) Shell account. If you can get shell, or command line access
    to the computer that is running the mud, then you can probably
    use an editor local to that computer (like vim) to edit files.
    	Chances are, though, that if you are a regular rank-and-file
    creator, you will not be given shell access. Most system admins
    consider giving random people off the net shell access
    an abomination.

    2) Server FTP/SFTP. The server that runs the mud might have an
    ftp server or sftpd access. Again, most security-conscious sysadmins
    will not permit Just Some Person Off The Internet to have this
    kind of access.

    3) Mud FTP. I don't like this option. Unix FTPD is a security
    concern as it is. Using unsupported, un-warrantied mud network code
    to provide ftp access to files seems to me to be equivalent to pulling
    down your pants, bending over, and whistling for the Internet to
    come visit. But...it's an option.

    4) Client upload. This is actually the most sensible option, if
    you are truly allergic to ed. You still need to use ed, but what
    you can do is write your code in your favorite local editor, like
    notepad or gvim or whatever. Then use your mud client (most of them
    have an option to "send text") to send the code by running ed,
    entering input mode, copying the code from your editor, and
    pasting it into your client.
    	This is a somewhat awkward system, and ill-suited to
    making minor changes. But it has the virtue of working well and
    being a widely available option.

    5) Suck it up. Really, you need to just get used to it. Don't
    make me tell you stories about how when I was younger I had to
    code using a VT terminal with no cut-and-paste, in an unheated,
    locked computer lab 20'x10' in size, at 9600 bps. In a snowstorm.
    Uphill both ways.

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