From: Jean Privat <jean@pryen.org>
Date: Fri, 21 Nov 2014 02:25:15 +0000 (-0500)
Subject: Merge: lib: add Float::is_approx to compare floats
X-Git-Tag: v0.6.11~23
X-Git-Url: http://nitlanguage.org?hp=9bb1267e3c47fc7168a9f9ef5605d2f563d00ff9

Merge: lib: add Float::is_approx to compare floats

Pull-Request: #922
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>
Reviewed-by: Alexandre Terrasa <alexandre@moz-code.org>
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>
---

diff --git a/lib/standard/kernel.nit b/lib/standard/kernel.nit
index 2e9c9ae..2f2df4b 100644
--- a/lib/standard/kernel.nit
+++ b/lib/standard/kernel.nit
@@ -331,6 +331,21 @@ universal Float
 		end
 	end
 
+	# Compare float numbers with a given precision.
+	#
+	# Because of the loss of precision in floating numbers,
+	# the `==` method is often not the best way to compare them.
+	#
+	# ~~~
+	# assert 0.01.is_approx(0.02, 0.1)   == true
+	# assert 0.01.is_approx(0.02, 0.001) == false
+	# ~~~
+	fun is_approx(other, precision: Float): Bool
+	do
+		assert precision >= 0.0
+		return self <= other + precision and self >= other - precision
+	end
+
 	redef fun max(other)
 	do
 		if self < other then
diff --git a/tests/sav/nitg-e/fixme/base_gen_reassign_alt4.res b/tests/sav/nitg-e/fixme/base_gen_reassign_alt4.res
index 56621b6..8229d05 100644
--- a/tests/sav/nitg-e/fixme/base_gen_reassign_alt4.res
+++ b/tests/sav/nitg-e/fixme/base_gen_reassign_alt4.res
@@ -1,4 +1,4 @@
-Runtime error: Cast failed. Expected `OTHER`, got `Float` (../lib/standard/kernel.nit:374)
+Runtime error: Cast failed. Expected `OTHER`, got `Float` (../lib/standard/kernel.nit:389)
 11
 21
 31
diff --git a/tests/sav/nitg-e/fixme/base_gen_reassign_alt5.res b/tests/sav/nitg-e/fixme/base_gen_reassign_alt5.res
index 56621b6..8229d05 100644
--- a/tests/sav/nitg-e/fixme/base_gen_reassign_alt5.res
+++ b/tests/sav/nitg-e/fixme/base_gen_reassign_alt5.res
@@ -1,4 +1,4 @@
-Runtime error: Cast failed. Expected `OTHER`, got `Float` (../lib/standard/kernel.nit:374)
+Runtime error: Cast failed. Expected `OTHER`, got `Float` (../lib/standard/kernel.nit:389)
 11
 21
 31
diff --git a/tests/sav/nitg-e/fixme/base_gen_reassign_alt6.res b/tests/sav/nitg-e/fixme/base_gen_reassign_alt6.res
index 56621b6..8229d05 100644
--- a/tests/sav/nitg-e/fixme/base_gen_reassign_alt6.res
+++ b/tests/sav/nitg-e/fixme/base_gen_reassign_alt6.res
@@ -1,4 +1,4 @@
-Runtime error: Cast failed. Expected `OTHER`, got `Float` (../lib/standard/kernel.nit:374)
+Runtime error: Cast failed. Expected `OTHER`, got `Float` (../lib/standard/kernel.nit:389)
 11
 21
 31
diff --git a/tests/sav/nituml_args3.res b/tests/sav/nituml_args3.res
index af28f14..e248df6 100644
--- a/tests/sav/nituml_args3.res
+++ b/tests/sav/nituml_args3.res
@@ -41,7 +41,7 @@ Bool [
 Object -> Bool [dir=back arrowtail=open style=dashed];
 
 Float [
- label = "{Float||}"
+ label = "{Float||+ is_approx(other: Float, precision: Float): Bool\l}"
 ]
 Numeric -> Float [dir=back arrowtail=open style=dashed];
 
diff --git a/tests/sav/nituml_args4.res b/tests/sav/nituml_args4.res
index 6189897..9a7b30f 100644
--- a/tests/sav/nituml_args4.res
+++ b/tests/sav/nituml_args4.res
@@ -41,7 +41,7 @@ Bool [
 Object -> Bool [dir=back arrowtail=open style=dashed];
 
 Float [
- label = "{Float||}"
+ label = "{Float||+ is_approx(other: Float, precision: Float): Bool\l}"
 ]
 Numeric -> Float [dir=back arrowtail=open style=dashed];