Refactoring Recipes

The intention of this page is to collect small refactoring snippets that one can/should apply to an existing OpenACS installation in order to improve and modernize its code base. Most of the recipes have already been applied to the official core packages.

Modernize Tcl

1. Refactor foreach {var1.. varN} $list {break} to lassign

   See http://wiki.tcl.tk/1530

   Deprecated code example

   foreach {dog cat} $animalslist break

   Recommended code example

   lassign $animalslist dog cat

   Command line for finding/replacing code

   todo

2. Refactor multiple lindex operations to lassign

   Deprecated code example

   set dog [lindex $animalslist 0]
set cat [lindex $animalslist 1]

   Recommended code example

   lassign $animalslist dog cat

   Command line for finding/replacing code

   todo

3. Brace expr expressions

   Deprecated code example

   [expr $money - 1]

   Recommended code example

   [expr {$money - 1}]

   Command line for finding/replacing code

   todo

4. Replace string equal with eq in expressions

   Deprecated code example

   if {[string equal "" $dog]} {error "I want a dog!"}

   Recommended code example

   if {$dog eq ""} {error "I want a dog!"}

   Command line for finding/replacing code

   todo

5. Replace lsearch with in or ni in expressions

   Deprecated code example

   if {[lsearch -exact $animalslist $dog] != -1 } {error "I dont want a dog!"}

   Recommended code example

   if {$dog in $animalslist} {error "I dont want a dog!"}

   Command line for finding/replacing code

   todo

6. Replace eval with {*} if possible

   Deprecated code example

   eval mycommand $args

   Recommended code example

   mycommand {*}$args

   Command line for finding/replacing code

   todo

Best Practices

1. Use bind variables in SQL statements

   Deprecated code example

   db_string check "SELECT * FROM animals WHERE color = $color;"

   Recommended code example

   db_string check "SELECT * FROM animals WHERE color = :color;"

   Command line for finding/replacing code

   todo

2. Use util::http instead of util_http*, ns_httpget, ::http, ::xo::HttpRequest

Substitute Deprecated Procedures

1. Replace empty_string_p with eq ""

   Deprecated code example

   if {[empty_string_p $dog]} {error "I want a dog!"}
if {![empty_string_p $cat]} {error "I dont want a cat!"}

   Recommended code example

   if {$dog eq ""} {error "I want a dog!"}
if {$cat ne ""} {error "I dont want a cat!"}

   Command line for finding/replacing code

   todo

   Rationale

   Byte-compiled comparisons are faster.

2. Replace exists_and_not_null with info exists and ne

   Deprecated code example

   if {[exists_and_not_null cat]} {error "I dont want a cat!"}

   Recommended code example

   if {[info exists cat] && $cat ne "" } {error "I dont want a cat!"}

   Command line for finding/replacing code

   todo

   Rationale

   Byte-compiled comparisons are faster.

3. Replace ad_parameter with parameter::get

   Deprecated code example

   ad_parameter -package_id 123 SystemURL ""

   Recommended code example

   parameter::get -package_id 123 SystemURL -default ""

   Command line for finding/replacing code

   todo

4. Replace ad_require_permission with permission::require_permission

   Deprecated code example

   ad_require_permission $oid "read"

   Recommended code example

   permission::require_permission -object_id $oid -privilege "read"

   Command line for finding/replacing code

   fgrep -rl "ad_require_permission" packages/ | xargs sed -i.sedbak -r 's/ad_require_permission\s+([^\s]*)\s+([^\s]*)/permission::require_permission -object_id \1 -privilege \2/g'

5. Replace util_unlist with lassign

   Deprecated code example

   util_unlist $animalslist dog cat

   Recommended code example

   lassign $animalslist dog cat

   Command line for finding/replacing code

   todo