Change action by system environment

separate provide function that help you to separate setting by system environment, such as system-name given by (system-name), Emacs version, OS, and so on.

How to Use?

Set your definition of system-predicate into separate-system-predicate-alist (optional), and use separate-setq or separate-cond. See also System-Predicate Section and Keywords Section.

;; Define some system-predicate. This is optional.
;; If you define this, you can use symbol as system-predicate(like condicate).
(setq separate-system-predicate-alist
      '(;; (symbol . system-predicate)
        (pc-name1 . "MY-PC-NAME1")
        (pc-name2 . "MY-PC-NAME2")
        (my-candicate . (:eval (abc)))
        ))

(separate-setq foo
  (;; (system-predicate . value)
   (pc-name1      . 1)
   (pc-name2      . 2)
   ("MY-PC-NAME3" . 3)
   (windows-nt    . 4)
   ((:eval (something) (bar))       . 5)
   ((:package-available 'baz)       . 6)
   ((:and windows-nt (:eval (def))) . 7)
   ((:system-predicates "MY-PC-NAME4" gnu/linux) . 8)
   (default . 0)))

Value of foo is set to:

1. If your system-name is “MY-PC-NAME1”: 1
2. Else if your system-name is “MY-PC-NAME2”: 2
3. Else if your system-name is “MY-PC-NAME3”: 3
4. Else if your system-type is winodows-nt: 4
5. Else if returned value by (something) (bar) is non-nil: 5
6. Else if (featurep 'baz) is non-nil: 6
7. Else if your system-type is windows-nt AND returned value by (def) is non-nil: 7
8. Else if your system-name is “MY-PC-NAME4” OR your system-type is gnu/linux: 8
9. If all of system-predicates are invalid: 0

System-Predicate

• system-predicate means object which can separate system environment.
• system-predicate can be list, symbol, number or string.

List

• There are 2 types of listed-system-predicate.
• One type is:
  • Have keyword in the car. All keywords start “:”.
  • cdr of the list is argument. See Keywords Section.
• The other type is:
  • Don’t have keyword in the car. This is put :system-predicates keyword automatically. See system-predicates Section.

Symbol

• This is interpreted as system-predicate defined in separate-system-predicate-alist,

or system-type (same as :os keyword). See separate-system-predicate-alist Section.

• the symbol default is special symbol. Element including this is evaluated only when all of other seprators are invalid.

;;Define symbol system-predicate.
(setq separate-system-predicate-alist
 '(
   ;; This system-predicate means "if `system-name' is "my-windows",".
   ;; See also String Section and :system-name Section.
   (my-win   . "my-windows")

   ;; This system-predicate means "if `system-type' is `gnu/linux' and
   ;; if `system-name' is "MY-PC,". See also String Section and
   ;; :and Section.
   (my-linux . (:and gnu/linux "MY-PC"))

   ;; You can make alias of symbol sparator.
   (my-l . my-linux)
 ))

(separate-setq foo
 (
  ;; If `system-name' is "my-windows", `foo' is set to 1.
  (my-win . 1)
  ;; If `system-type' is `gnu/linux' and if `system-name' is "MY-PC,
  ;; `foo' is set to 2.
  (my-linux . 2)
  ;; Otherwise, `foo' is set to 3.
  (default . 3)
  ))

;; below is absolutely same as above.
(separate-setq foo
 (
  (my-win . 1)
  (default . 3)                         ; You can write default anywhere.
  (my-linux . 2)
  ))

Number

This is interpreted as has :emacs-version>= keyword. See emacs-version Section.

String

This is interpreted as has :system-name keyword. See system-name Section.

Keywords

:system-name

• This keyword accept multiple argument of string. if at least one of argument is same as system-name, this system-predicate is valid.
• Keyword :system-name is optional.

(separate-setq foo
  (;; (system-predicate . value)

  ;; if system-name is "MY-PC-1", `foo' is
  ;; set to 1
  ((:system-name "MY-PC-1") . 1)

  ;; :system-name is optional.
  ;; So This is same as ((:system-name "MY-PC-2") . 2)
  ("MY-PC-2" . 2)

  ;; you can put multiple argument.
  ;; If system-name is either "MY-PC-3" or "MY-PC-4",
  ;; `foo' is set to 3
  ((:system-name "MY-PC-3" "MY-PC-4") . 3)

  ;; :system-name is optional even when multiple argument.
  (("MY-PC-6" "MY-PC-7" "MY-PC-8") . 4)
))

:emacs-version>=

• This keyword accept 1 or 2 argument(s) of number. First argument is M, and second argument (optional) is m. If emacs version is same or higher than M.m, this system-predicate is valid.
• If you use only first argument, you can write number of major-version as system-predicate.

(separate-setq foo
  (
   ;; If emacs version is 25.3 or higher, `foo' is set to 1
   ((:emacs-version>= 25 3) . 1)

   ;; If emacs version is 25(.0) or higher, `foo' is set to 2
   ((:emacs-version>= 25) . 2)

   ;; Same as previous one.
   (25 . 2)
   ))

:eval

• This keyword accept multiple arguments of S expression. If returned value of those S expression is non-nil, this system-predicate is valid.

(separate-setq foo
   (
    ;; If system-name include the string "WIN",
    ;; `foo' is set to 1
    ((:eval (string-match "WIN" (system-name))) . 1)

    ;; multiple S expressions is permitted.
    ;; If `(progn (bar) (baz))' return t, `foo' is set to 5
    ((:eval (bar) (baz)) . 5)

    ;; This is similar to `(default . 2)', but in this case,
    ;; cons-cells below this one will NOT seen, while all cons-cells
    ;; are seen in case of "default".
    ((:eval t) . 2)

    ;; This cons-cell is not seen. In the other words, `foo' is never set
    ;; to 3.
    ("SOME-PC" . 3)
   ))

:os

• This keyword accept multiple arguments of symbol. If one of arguments is same as system-type, this system-predicate is valid. See also emacs help of system-type, and system-predicates Section.
• Keyword :os is optional.

(separate-setq foo
(
 ;; If OS is Windows, `foo' is set to 1.
 ((:os windos-nt) . 1)

 ;; multiple arguments is permitted.
 ;; If OS is either GNU/Linux or Cygwin (even not OS),
 ;; `foo' is set to 2.
 ((:os gnu/linux cygwin) . 2)

 ;; their symbols of `system-type' can be used as symbol system-predicate defined in
 ;; `separate-system-predicate-alist'. So you can write this instead of above.
 ;; See also :system-predicates Seciton.
 ((gnu/linux cygwin) . 2)
))

:package-available

• This keyword accept multiple argument of feature (symbol). If all arguments are returned non-nil when passed to featurep, this system-predicate is valid.

(separate-setq foo
 (
  ;; If cl-lib is provided (meaning `(featurep 'cl-lib)' return t),
  ;; `foo' is set to 1
  ((:package-available cl-lib) . 1)

  ;; Multiple arguments are permitted.
  ;; Only if `helm', `company', and `ido' is all provided,
  ;; `foo' is set to 2.
  ((:package-available helm company ido) . 2)
 ))

:system-predicates / :alias / :or

• These keywords accept multiple arguments of system-predicate. If at least one of system-predicates of arguments is valid, this system-predicate is valid.
• those keywords are optional.

(separate-setq foo
  (;; (system-predicate . value)

  ;; if system-name is "MY-PC-1" or "MY-PC-2", or if system-type
  ;; is `windows-nt', `foo' is set to 1.
  ((:system-predicates                         ; This can be `:or' or `:alias'
    (:system-name "MY-PC-1")
    "MY-PC-2"
    windows-nt)
    . 1)

  ;; You can use this keyword with all system-predicate.
  ;; If cl-lib and ido is all provided, or if `bar' is a function,
  ;; `foo' is set to 2.
  ((:or
   (:package-available cl-lib ido)
   (:eval (functionp 'bar)))
   . 2)
))

:and

• These keywords accept multiple arguments of system-predicate. If all system-predicates of arguments are valid, this system-predicate is valid.

(separate-setq foo
    (;; (system-predicate . value)

    ;; if system-name is "MY-PC-1", AND if system-type is `windows-nt',
    ;; `foo' is set to 1.
    ((:and
      (:system-name "MY-PC-1")
      windows-nt)
      . 1)

    ;; You can use this keyword with all system-predicate.
    ;; If cl-lib and ido is all provided, AND if `bar' is a function,
    ;; `foo' is set to 2.
    ((:or
     (:package-available cl-lib ido)
     (:eval (functionp 'bar)))
     . 2)
  ))

Variables

separate-system-predicate-alist

• An associated list. Each element is cons cell, (symbol . system-predicate). In this package, you can use the symbol as the system-predicate.
• See also How to Use Section as example.
• In the future, we will provide some functions to define symbol-system-predicate like this.

Macros

separate-set (variable alist)

• Set value of VARIABLE depend on SYSTEM-PREDICATE below.
• Each element of ALIST is (SYSTEM-PREDICATE . VALUE), and VARIABLE is set to VALUE if SYSTEM-PREDICATE is valid.
• If there are some cons cells whose car (= SYSTEM-PREDICATE) is valid, upstream element is used, and rest of them is not evaluated.
• in the cons cell whose SYSTEM-PREDICATE is default, its VALUE is used only when any other SYSTEM-PREDICATE isn’t valid.
• (separate-set 'a ((b . c) ...)) is absolutely same as (separate-setq a ((b . c) ...)).

separate-setq (variable alist)

• Same as separate-set, but VARIABLE doesn’t have to be quoted.
• See How to Use Section as example.

separate-set-no-eval (variable alist)

• Same as separate-set-no-eval, but VALUE are NOT evalueted.

separate-setq-no-eval (variable alist)

• Same as separate-setq-no-eval, but VALUE are NOT evalueted.

separate-cond (&body clauses)

• Similar to cond, but use SYSTEM-PREDICATE instead of CANDICATE. If SYSTEM-PREDICATE is valid, evaluate BODY.
• Priority of each clause is same as separate-set.

;; Define some system-predicate. This is optional.
;; If you define this, you can use symbol as system-predicate(like condicate).
(setq separate-system-predicate-alist
      '(;; (symbol . system-predicate)
        (pc-name1 . "MY-PC-NAME1")
        (pc-name2 . "MY-PC-NAME2")
        (my-candicate . (:eval (abc)))
        ))

(separate-cond
  ;; (system-predicate . value)
   (pc-name1       1)
   (pc-name2       2)
   ("MY-PC-NAME3"  3)
   (windows-nt     4)
   ((:eval (something) (bar))       5)
   ((:package-available 'baz)       6)
   ((:and windows-nt (:eval (def))) 7)
   ((:system-predicates "MY-PC-NAME4" gnu/linux) 8)
   (default 0))

The latter S expression returns:

1. If your system-name is “MY-PC-NAME1”: 1
2. Else if your system-name is “MY-PC-NAME2”: 2
3. Else if your system-name is “MY-PC-NAME3”: 3
4. Else if your system-type is winodows-nt: 4
5. Else if returned value by (something) (bar) is non-nil: 5
6. Else if (featurep 'baz) is non-nil: 6
7. Else if your system-type is windows-nt AND returned value by (def) is non-nil: 7
8. Else if your system-name is “MY-PC-NAME4” OR your system-type is gnu/linux: 8
9. If all of system-predicates are invalid: 0

License

This package is licensed by GPLv3. See LICENSE.