lazily initialize the default logger

In order for the user to configure the logging behavior the values
of lspc.logging and lspc.log_file must be evaluated after vis-lspc
was required.
To lazily evaluate the logging configuration a new
LazyInitLogger metatable is introduced, which initializes the
actual logger on first use.

Fixes: 1bd1416c89f92f637ca5e22c94b3479f8d32f2d7

2 files changed, 30 insertions, 1 deletions

diff --git a/init.lua b/init.lua
index 15d03b5..9906f29 100644
--- a/init.lua
+++ b/init.lua
@@ -27,7 +27,7 @@ local source_path = source_str:match('(.*/)')
 local lspc = dofile(source_path .. 'lspc.lua')
 
 -- initialise the logging system
-lspc.logger = dofile(source_path .. 'log.lua').new('lspc', lspc.logging, lspc.log_file)
+lspc.logger = dofile(source_path .. 'log.lua').lazyNew('lspc', lspc)
 
 local parser = dofile(source_path .. 'parser.lua')
 
diff --git a/log.lua b/log.lua
index 789522d..a41b819 100644
--- a/log.lua
+++ b/log.lua
@@ -23,6 +23,35 @@ end
 function DummyLogger.close()
 end
 
+--- Logger that initialises itself on first use
+local LazyInitLogger = {}
+function LazyInitLogger:log(first_msg)
+  self.logger = log.new(self.name, self.conf.logging, self.conf.log_file)
+  self.log = function(lazyLogger, msg)
+    lazyLogger.logger:log(msg)
+  end
+  self.logger:log(first_msg)
+end
+function LazyInitLogger:close()
+  self.logger:close()
+end
+
+--- Create a new lazily initializing logger
+--
+-- The created logger will initialize itself using log.new on first use.
+-- The logging and log_file fields of the conf table are passed to log.new.
+-- @param name The name of the logger
+-- @param conf Table containing logging and log_file members
+function log.lazyNew(name, conf)
+  local logger = {name = name, conf = conf}
+  setmetatable(logger, {__index = LazyInitLogger})
+  return logger
+end
+
+--- Create a new named logger
+-- @param name The name of the logger
+-- @param logging Is logging enabled
+-- @param log_file File path to the log file to use
 function log.new(name, logging, log_file)
   local logger = {name = name, log_fd = nil}