Basic Examples

In[11]:=
[◼]
ReplaceAllUnheld
[If[a,a,a],a->b]
Out[11]=
If[b,a,a]

Scope 
(2)
 

Functions that hold some of their arguments:
In[12]:=
SetAttributes[hf,HoldFirst]
In[13]:=
SetAttributes[hr,HoldRest]
In[14]:=
[◼]
ReplaceAllUnheld
[{hf[x,x],hr[x,x]},x1]
Out[14]=
{hf[x,1],hr[1,x]}
———
Explicitly held expressions:
In[15]:=
[◼]
ReplaceAllUnheld
[{x,Hold[x],Unevaluated[x]},x1]
Out[15]=
{1,Hold[x],Unevaluated[x]}

Properties and Relations 
(1)
 


Possible Issues 
(1)
 
